Simple Doc Fixes (#35743)

* Fix "the a" typos

* Rephrase global key API doc description

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

@@ -83,8 +83,8 @@ class ObjectKey extends LocalKey {
 /// A key that is unique across the entire app.
 ///
 /// Global keys uniquely identify elements. Global keys provide access to other
-/// objects that are associated with elements, such as the a [BuildContext] and,
-/// for [StatefulWidget]s, a [State].
+/// objects that are associated with those elements, such as [BuildContext].
+/// For [StatefulWidget]s, global keys also provide access to [State].
 ///
 /// Widgets that have global keys reparent their subtrees when they are moved
 /// from one location in the tree to another location in the tree. In order to

packages/flutter_test/lib/src/matchers.dart

@@ -84,7 +84,7 @@ const Matcher findsOneWidget = _FindsWidgetMatcher(1, 1);
 ///  * [findsOneWidget], when you want the finder to find exactly one widget.
 Matcher findsNWidgets(int n) => _FindsWidgetMatcher(n, n);
 
-/// Asserts that the [Finder] locates the a single widget that has at
+/// Asserts that the [Finder] locates a single widget that has at
 /// least one [Offstage] widget ancestor.
 ///
 /// It's important to use a full finder, since by default finders exclude
@@ -101,7 +101,7 @@ Matcher findsNWidgets(int n) => _FindsWidgetMatcher(n, n);
 ///  * [isOnstage], the opposite.
 const Matcher isOffstage = _IsOffstage();
 
-/// Asserts that the [Finder] locates the a single widget that has no
+/// Asserts that the [Finder] locates a single widget that has no
 /// [Offstage] widget ancestors.
 ///
 /// See also:
@@ -109,7 +109,7 @@ const Matcher isOffstage = _IsOffstage();
 ///  * [isOffstage], the opposite.
 const Matcher isOnstage = _IsOnstage();
 
-/// Asserts that the [Finder] locates the a single widget that has at
+/// Asserts that the [Finder] locates a single widget that has at
 /// least one [Card] widget ancestor.
 ///
 /// See also:
@@ -117,7 +117,7 @@ const Matcher isOnstage = _IsOnstage();
 ///  * [isNotInCard], the opposite.
 const Matcher isInCard = _IsInCard();
 
-/// Asserts that the [Finder] locates the a single widget that has no
+/// Asserts that the [Finder] locates a single widget that has no
 /// [Card] widget ancestors.
 ///
 /// This is equivalent to `isNot(isInCard)`.