Fix common typos in doc comments (#6520)

packages/flutter/lib/src/painting/text_editing.dart

@@ -41,7 +41,7 @@ class TextRange {
   /// Whether this range is empty (but still potentially placed inside the text).
   bool get isCollapsed => start == end;
 
-  /// Whether the start of this range preceeds the end.
+  /// Whether the start of this range precedes the end.
   bool get isNormalized => end >= start;
 
   /// The text before this range.

packages/flutter/lib/src/painting/text_span.dart

@@ -62,13 +62,13 @@ class TextSpan {
 
   /// The text contained in the span.
   ///
-  /// If both [text] and [children] are non-null, the text will preceed the
+  /// If both [text] and [children] are non-null, the text will precede the
   /// children.
   final String text;
 
   /// Additional spans to include as children.
   ///
-  /// If both [text] and [children] are non-null, the text will preceed the
+  /// If both [text] and [children] are non-null, the text will precede the
   /// children.
   ///
   /// Modifying the list after the [TextSpan] has been created is not

packages/flutter/lib/src/rendering/box.dart

@@ -90,7 +90,7 @@ class BoxConstraints extends Constraints {
       minHeight = 0.0,
       maxHeight = size.height;
 
-  /// Creates box constraints that expand to fill another box contraints.
+  /// Creates box constraints that expand to fill another box constraints.
   ///
   /// If width or height is given, the constraints will require exactly the
   /// given value in the given dimension.

packages/flutter/lib/src/rendering/flex.dart

@@ -45,7 +45,7 @@ class FlexParentData extends ContainerBoxParentDataMixin<RenderBox> {
 /// During a flex layout, available space along the main axis is allocated to
 /// children. After allocating space, there might be some remaining free space.
 /// This value controls whether to maximize or minimize the amount of free
-/// space, subject to the incoming layout contraints.
+/// space, subject to the incoming layout constraints.
 ///
 /// See [Row], [Column], [MainAxisAlignment], [Flexible].
 enum MainAxisSize {
@@ -169,7 +169,7 @@ class RenderFlex extends RenderBox with ContainerRenderObjectMixin<RenderBox, Fl
   ///
   /// After allocating space to children, there might be some remaining free
   /// space. This value controls whether to maximize or minimize the amount of
-  /// free space, subject to the incoming layout contraints.
+  /// free space, subject to the incoming layout constraints.
   ///
   /// If some children have a non-zero flex factors (and none have a fit of
   /// [FlexFit.loose]), they will expand to consume all the available space and

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

@@ -1911,7 +1911,7 @@ class Flex extends MultiChildRenderObjectWidget {
   ///
   /// After allocating space to children, there might be some remaining free
   /// space. This value controls whether to maximize or minimize the amount of
-  /// free space, subject to the incoming layout contraints.
+  /// free space, subject to the incoming layout constraints.
   ///
   /// If some children have a non-zero flex factors (and none have a fit of
   /// [FlexFit.loose]), they will expand to consume all the available space and

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

@@ -1996,7 +1996,7 @@ abstract class Element implements BuildContext {
   /// The framework calls this function when a newly created element is added to
   /// the tree for the first time. Use this method to initialize state that
   /// depends on having a parent. State that is independent of the parent can
-  /// more easily be initialized in the contructor.
+  /// more easily be initialized in the constructor.
   ///
   /// This method transitions the element from the "initial" lifecycle state to
   /// the "active" lifecycle state.

packages/flutter_driver/lib/src/driver.dart

@@ -253,7 +253,7 @@ class FlutterDriver {
   ///
   /// [dx] and [dy] specify the total offset for the entire scrolling action.
   ///
-  /// [duration] specifies the lenght of the action.
+  /// [duration] specifies the length of the action.
   ///
   /// The move events are generated at a given [frequency] in Hz (or events per
   /// second). It defaults to 60Hz.

packages/flutter_markdown/lib/src/markdown_style_raw.dart

@@ -34,7 +34,7 @@ class MarkdownStyleRaw {
   }
 
   /// Creates a new [MarkdownStyleRaw] based on the current style, with the
-  /// provided paramaters overridden.
+  /// provided parameters overridden.
   MarkdownStyleRaw copyWith({
     TextStyle a,
     TextStyle p,