remove "the" duplications (flutter#14952)

Author: najeira

examples/flutter_gallery/lib/demo/animation/home.dart

@@ -407,7 +407,7 @@ class _SnappingScrollPhysics extends ClampingScrollPhysics {
         return _toZeroScrollOffsetSimulation(offset, dragVelocity);
     } else {
       // The user ended the drag with little or no velocity. If they
-      // didn't leave the the offset above midScrollOffset, then
+      // didn't leave the offset above midScrollOffset, then
       // snap to midScrollOffset if they're more than halfway there,
       // otherwise snap to zero.
       final double snapThreshold = midScrollOffset / 2.0;

packages/flutter/lib/src/gestures/velocity_tracker.dart

@@ -79,7 +79,7 @@ class Velocity {
 /// A two dimensional velocity estimate.
 ///
 /// VelocityEstimates are computed by [VelocityTracker.getVelocityEstimate]. An
-/// estimate's [confidence] measures how well the the velocity tracker's position
+/// estimate's [confidence] measures how well the velocity tracker's position
 /// data fit a straight line, [duration] is the time that elapsed between the
 /// first and last position sample used to compute the velocity, and [offset]
 /// is similarly the difference between the first and last positions.

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

@@ -209,7 +209,7 @@ class AppBar extends StatefulWidget implements PreferredSizeWidget {
   final List<Widget> actions;
 
   /// This widget is stacked behind the toolbar and the tabbar. It's height will
-  /// be the same as the the app bar's overall height.
+  /// be the same as the app bar's overall height.
   ///
   /// A flexible space isn't actually flexible unless the [AppBar]'s container
   /// changes the [AppBar]'s size. A [SliverAppBar] in a [CustomScrollView]
@@ -795,7 +795,7 @@ class SliverAppBar extends StatefulWidget {
   final List<Widget> actions;
 
   /// This widget is stacked behind the toolbar and the tabbar. It's height will
-  /// be the same as the the app bar's overall height.
+  /// be the same as the app bar's overall height.
   ///
   /// Typically a [FlexibleSpaceBar]. See [FlexibleSpaceBar] for details.
   final Widget flexibleSpace;

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

@@ -229,7 +229,7 @@ class MaterialButton extends StatelessWidget {
   /// The color to use for this button's text.
   final Color textColor;
 
-  /// The the button's fill color, displayed by its [Material], while the button
+  /// The button's fill color, displayed by its [Material], while the button
   /// is in its default (unpressed, enabled) state.
   ///
   /// Defaults to null, meaning that the color is automatically derived from the [Theme].

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

@@ -446,7 +446,7 @@ class _DragAnimation extends Animation<double> with AnimationWithParentMixin<dou
   }
 }
 
-// This class, and TabBarScrollController, only exist to handle the the case
+// This class, and TabBarScrollController, only exist to handle the case
 // where a scrollable TabBar has a non-zero initialIndex. In that case we can
 // only compute the scroll position's initial scroll offset (the "correct"
 // pixels value) after the TabBar viewport width and scroll limits are known.
@@ -476,7 +476,7 @@ class _TabBarScrollPosition extends ScrollPositionWithSingleContext {
   }
 }
 
-// This class, and TabBarScrollPosition, only exist to handle the the case
+// This class, and TabBarScrollPosition, only exist to handle the case
 // where a scrollable TabBar has a non-zero initialIndex.
 class _TabBarScrollController extends ScrollController {
   _TabBarScrollController(this.tabBar);

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

@@ -135,7 +135,7 @@ class BorderSide {
   ///
   /// The `t` argument represents the multiplicand, or the position on the
   /// timeline for an interpolation from nothing to `this`, with 0.0 meaning
-  /// that the the object returned should be the nil variant of this object, 1.0
+  /// that the object returned should be the nil variant of this object, 1.0
   /// meaning that no change should be applied, returning `this` (or something
   /// equivalent to `this`), and other values meaning that the object should be
   /// multiplied by `t`. Negative values are treated like zero.
@@ -328,7 +328,7 @@ abstract class ShapeBorder {
   ///
   /// The `t` argument represents the multiplicand, or the position on the
   /// timeline for an interpolation from nothing to `this`, with 0.0 meaning
-  /// that the the object returned should be the nil variant of this object, 1.0
+  /// that the object returned should be the nil variant of this object, 1.0
   /// meaning that no change should be applied, returning `this` (or something
   /// equivalent to `this`), and other values meaning that the object should be
   /// multiplied by `t`. Negative values are allowed but may be meaningless

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

@@ -642,7 +642,7 @@ class RenderFlex extends RenderBox with ContainerRenderObjectMixin<RenderBox, Fl
     final bool canFlex = maxMainSize < double.INFINITY;
 
     double crossSize = 0.0;
-    double allocatedSize = 0.0; // Sum of the sizes of the the non-flexible children.
+    double allocatedSize = 0.0; // Sum of the sizes of the non-flexible children.
     RenderBox child = firstChild;
     RenderBox lastFlexChild;
     while (child != null) {

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

@@ -1854,7 +1854,7 @@ abstract class RenderObject extends AbstractNode with DiagnosticableTreeMixin im
   /// Mark this render object as having changed its visual appearance.
   ///
   /// Rather than eagerly updating this render object's display list
-  /// in response to writes, we instead mark the the render object as needing to
+  /// in response to writes, we instead mark the render object as needing to
   /// paint, which schedules a visual update. As part of the visual update, the
   /// rendering pipeline will give this render object an opportunity to update
   /// its display list.

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

@@ -120,7 +120,7 @@ class TableBorder {
   ///
   /// The `t` argument represents the multiplicand, or the position on the
   /// timeline for an interpolation from nothing to `this`, with 0.0 meaning
-  /// that the the object returned should be the nil variant of this object, 1.0
+  /// that the object returned should be the nil variant of this object, 1.0
   /// meaning that no change should be applied, returning `this` (or something
   /// equivalent to `this`), and other values meaning that the object should be
   /// multiplied by `t`. Negative values are treated like zero.

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

@@ -147,7 +147,7 @@ class TextSelection extends TextRange {
   /// Might be larger than, smaller than, or equal to base.
   final int extentOffset;
 
-  /// If the the text range is collapsed and has more than one visual location
+  /// If the text range is collapsed and has more than one visual location
   /// (e.g., occurs at a line break), which of the two locations to use when
   /// painting the caret.
   final TextAffinity affinity;