Rename InputFormField to TextField

This patch is the first of a series to rationalize the names of the text-input
related widgets.

See #7031

examples/flutter_gallery/lib/demo/expansion_panels_demo.dart

@@ -205,7 +205,7 @@ class _ExpansionPanelsDemoState extends State<ExpasionPanelsDemo> {
                   onCancel: () { Form.of(context).reset(); close(); },
                   child: new Padding(
                     padding: const EdgeInsets.symmetric(horizontal: 16.0),
-                    child: new InputFormField(
+                    child: new TextField(
                       hintText: item.hint,
                       labelText: item.name,
                       initialValue: new InputValue(text: item.value),

examples/flutter_gallery/lib/demo/text_field_demo.dart

@@ -113,7 +113,7 @@ class TextFieldDemoState extends State<TextFieldDemo> {
         child: new Block(
           padding: const EdgeInsets.symmetric(horizontal: 16.0),
           children: <Widget>[
-            // It's simpler to use an InputFormField, as below, but a FormField
+            // It's simpler to use an TextField, as below, but a FormField
             // that builds an Input is equivalent.
             new FormField<InputValue>(
               initialValue: InputValue.empty,
@@ -130,7 +130,7 @@ class TextFieldDemoState extends State<TextFieldDemo> {
                 );
               },
             ),
-            new InputFormField(
+            new TextField(
               icon: new Icon(Icons.phone),
               hintText: 'Where can we reach you?',
               labelText: 'Phone Number',
@@ -138,7 +138,7 @@ class TextFieldDemoState extends State<TextFieldDemo> {
               onSaved: (InputValue val) { person.phoneNumber = val.text; },
               validator: _validatePhoneNumber,
             ),
-            new InputFormField(
+            new TextField(
               hintText: 'Tell us about yourself (optional)',
               labelText: 'Life story',
               maxLines: 3,
@@ -147,7 +147,7 @@ class TextFieldDemoState extends State<TextFieldDemo> {
               crossAxisAlignment: CrossAxisAlignment.start,
               children: <Widget>[
                 new Expanded(
-                  child: new InputFormField(
+                  child: new TextField(
                     key: _passwordFieldKey,
                     hintText: 'How do you log in?',
                     labelText: 'New Password',
@@ -157,7 +157,7 @@ class TextFieldDemoState extends State<TextFieldDemo> {
                 ),
                 new SizedBox(width: 16.0),
                 new Expanded(
-                  child: new InputFormField(
+                  child: new TextField(
                     hintText: 'How do you log in?',
                     labelText: 'Re-type Password',
                     hideText: true,

packages/flutter/lib/src/material/input.dart

@@ -386,7 +386,7 @@ class _InputContainerState extends State<InputContainer> {
 ///
 /// Requires one of its ancestors to be a [Material] widget.
 ///
-/// When using inside a [Form], consider using [InputFormField] instead.
+/// When using inside a [Form], consider using [TextField] instead.
 ///
 /// Assuming that the input is already focused, the basic data flow for
 /// retrieving user input is:
@@ -402,14 +402,14 @@ class _InputContainerState extends State<InputContainer> {
 /// See also:
 ///
 ///  * <https://material.google.com/components/text-fields.html>
-///  * [InputFormField], which simplifies steps 2-4 above.
+///  * [TextField], which simplifies steps 2-4 above.
 class Input extends StatefulWidget {
   /// Creates a text input field.
   ///
   /// By default, the input uses a keyboard appropriate for text entry.
   //
-  //  If you change this constructor signature, please also update
-  // InputContainer, InputFormField, InputField.
+  // If you change this constructor signature, please also update
+  // InputContainer, TextField, InputField.
   Input({
     Key key,
     this.value,
@@ -553,10 +553,10 @@ class _InputState extends State<Input> {
 /// pass a [GlobalKey] to the constructor and use [GlobalKey.currentState] to
 /// save or reset the form field.
 ///
-/// To see the use of [InputFormField], compare these two ways of a implementing
+/// To see the use of [TextField], compare these two ways of a implementing
 /// a simple two text field form.
 ///
-/// Using [InputFormField]:
+/// Using [TextField]:
 ///
 /// ```dart
 /// String _firstName, _lastName;
@@ -566,11 +566,11 @@ class _InputState extends State<Input> {
 ///   key: _formKey,
 ///   child: new Row(
 ///     children: <Widget>[
-///       new InputFormField(
+///       new TextField(
 ///         labelText: 'First Name',
 ///         onSaved: (InputValue value) { _firstName = value.text; }
 ///       ),
-///       new InputFormField(
+///       new TextField(
 ///         labelText: 'Last Name',
 ///         onSaved: (InputValue value) { _lastName = value.text; }
 ///       ),
@@ -613,8 +613,8 @@ class _InputState extends State<Input> {
 ///     ),
 ///  )
 /// ```
-class InputFormField extends FormField<InputValue> {
-  InputFormField({
+class TextField extends FormField<InputValue> {
+  TextField({
     Key key,
     GlobalKey focusKey,
     TextInputType keyboardType: TextInputType.text,

packages/flutter/lib/src/widgets/form.dart

@@ -197,7 +197,10 @@ typedef Widget FormFieldBuilder<T>(FormFieldState<T> field);
 /// pass a [GlobalKey] to the constructor and use [GlobalKey.currentState] to
 /// save or reset the form field.
 ///
-/// See also: [Form], [InputFormField]
+/// See also:
+///
+///  * [Form], which is the widget that aggregates the form fields.
+///  * [TextField], which is a commonly used form field for entering text.
 class FormField<T> extends StatefulWidget {
   FormField({
     Key key,

packages/flutter/test/material/will_pop_test.dart

@@ -46,7 +46,7 @@ class SampleForm extends StatelessWidget {
             willPopCount += 1;
             return callback();
           },
-          child: new InputFormField(),
+          child: new TextField(),
         ),
       ),
     );

packages/flutter/test/widgets/form_test.dart

@@ -29,7 +29,7 @@ void main() {
         child: new Material(
           child: new Form(
             key: formKey,
-            child: new InputFormField(
+            child: new TextField(
               onSaved: (InputValue value) { fieldValue = value.text; },
             ),
           )
@@ -61,7 +61,7 @@ void main() {
       return new Center(
         child: new Material(
           child: new Form(
-            child: new InputFormField(
+            child: new TextField(
               onChanged: (InputValue value) { fieldValue = value.text; },
             ),
           )
@@ -96,7 +96,7 @@ void main() {
           child: new Form(
             key: formKey,
             autovalidate: autovalidate,
-            child: new InputFormField(
+            child: new TextField(
               key: inputKey,
               validator: errorText,
             ),
@@ -151,10 +151,10 @@ void main() {
               key: focusKey,
               child: new Block(
                 children: <Widget>[
-                  new InputFormField(
+                  new TextField(
                     key: fieldKey
                   ),
-                  new InputFormField(
+                  new TextField(
                     validator: errorText,
                   ),
                 ]
@@ -190,7 +190,7 @@ void main() {
       return new Center(
         child: new Material(
           child: new Form(
-            child: new InputFormField(
+            child: new TextField(
               key: inputKey,
               initialValue: new InputValue(text: initialValue),
             ),
@@ -229,7 +229,7 @@ void main() {
         child: new Material(
           child: new Form(
             key: formKey,
-            child: remove ? new Container() : new InputFormField(
+            child: remove ? new Container() : new TextField(
               key: fieldKey,
               autofocus: true,
               onSaved: (InputValue value) { fieldValue = value.text; },