Updated some links (#32444)

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

@@ -551,7 +551,7 @@ class ContainerLayer extends Layer {
   List<PictureLayer> _processConflictingPhysicalLayers(PhysicalModelLayer predecessor, PhysicalModelLayer child) {
     FlutterError.reportError(FlutterErrorDetails(
       exception: FlutterError('Painting order is out of order with respect to elevation.\n'
-                              'See https://api.flutter.dev/flutter/rendering/debugCheckElevations.html '
+                              'See https://api.flutter.dev/flutter/rendering/debugCheckElevationsEnabled.html '
                               'for more details.'),
       library: 'rendering library',
       context: ErrorDescription('during compositing'),

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

@@ -86,6 +86,7 @@ bool debugPrintGlobalKeyedWidgetLifecycle = false;
 ///
 /// For details on how to use [Timeline] events in the Dart Observatory to
 /// optimize your app, see https://flutter.dev/docs/testing/debugging#tracing-any-dart-code-performance
+/// and https://fuchsia.googlesource.com/topaz/+/master/shell/docs/performance.md
 ///
 /// See also [debugProfilePaintsEnabled], which does something similar but for
 /// painting, and [debugPrintRebuildDirtyWidgets], which does something similar

packages/flutter_test/lib/src/test_compat.dart

@@ -129,7 +129,7 @@ Future<void> _runSkippedTest(Suite suiteConfig, Test test, List<Group> parents,
 /// If [retry] is passed, the test will be retried the provided number of times
 /// before being marked as a failure.
 ///
-/// [configuring tags]: https://github.com/dart-lang/test/blob/master/doc/package_config.md#configuring-tags
+/// [configuring tags]: https://github.com/dart-lang/test/blob/44d6cb196f34a93a975ed5f3cb76afcc3a7b39b0/doc/package_config.md#configuring-tags
 ///
 /// [onPlatform] allows tests to be configured on a platform-by-platform
 /// basis. It's a map from strings that are parsed as [PlatformSelector]s to
@@ -204,7 +204,7 @@ void test(
 /// [package configuration file][configuring tags]. The parameter can be an
 /// [Iterable] of tag names, or a [String] representing a single tag.
 ///
-/// [configuring tags]: https://github.com/dart-lang/test/blob/master/doc/package_config.md#configuring-tags
+/// [configuring tags]: https://github.com/dart-lang/test/blob/44d6cb196f34a93a975ed5f3cb76afcc3a7b39b0/doc/package_config.md#configuring-tags
 ///
 /// [onPlatform] allows groups to be configured on a platform-by-platform
 /// basis. It's a map from strings that are parsed as [PlatformSelector]s to