Whitespace fixes to make Travis happy (#19611)

Follow-up to https://github.com/flutter/flutter/pull/18562, which passed Travis before the check was added.

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

@@ -163,16 +163,16 @@ class TextField extends StatefulWidget {
   /// Defaults to [TextInputAction.done]. Must not be null.
   final TextInputAction textInputAction;
 
-  /// Configures how the platform keyboard will select an uppercase or 
+  /// Configures how the platform keyboard will select an uppercase or
   /// lowercase keyboard.
   ///
   /// Only supports text keyboards, other keyboard types will ignore this
   /// configuration. Capitalization is locale-aware.
   ///
   /// Defaults to [TextCapitalization.none]. Must not be null.
-  /// 
+  ///
   /// See also:
-  /// 
+  ///
   ///   * [TextCapitalization], for a description of each capitalization behavior.
   final TextCapitalization textCapitalization;
 

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

@@ -272,16 +272,16 @@ class EditableText extends StatefulWidget {
   /// Defaults to the ambient [Directionality], if any.
   final TextDirection textDirection;
 
-  /// Configures how the platform keyboard will select an uppercase or 
+  /// Configures how the platform keyboard will select an uppercase or
   /// lowercase keyboard.
   ///
   /// Only supports text keyboards, other keyboard types will ignore this
   /// configuration. Capitalization is locale-aware.
-  /// 
+  ///
   /// Defaults to [TextCapitalization.none]. Must not be null.
-  /// 
+  ///
   /// See also:
-  /// 
+  ///
   ///   * [TextCapitalization], for a description of each capitalization behavior.
   final TextCapitalization textCapitalization;