Add support for --track-widget-creation back to ios build rules. (#18046)

packages/flutter_tools/lib/src/build_info.dart

diff --git a/packages/flutter_tools/lib/src/build_info.dart b/packages/flutter_tools/lib/src/build_info.dart
index 2472b9d..f481bf6 100644
--- a/packages/flutter_tools/lib/src/build_info.dart
+++ b/packages/flutter_tools/lib/src/build_info.dart
@@ -12,7 +12,7 @@
 class BuildInfo {
   const BuildInfo(this.mode, this.flavor, {
     this.previewDart2: false,
-    this.trackWidgetCreation,
+    this.trackWidgetCreation: false,
     this.extraFrontEndOptions,
     this.extraGenSnapshotOptions,
     this.preferSharedLibrary,

packages/flutter_tools/lib/src/ios/simulators.dart

diff --git a/packages/flutter_tools/lib/src/ios/simulators.dart b/packages/flutter_tools/lib/src/ios/simulators.dart
index 6ad3a20..d6036b9 100644
--- a/packages/flutter_tools/lib/src/ios/simulators.dart
+++ b/packages/flutter_tools/lib/src/ios/simulators.dart
@@ -363,6 +363,7 @@
 
     final BuildInfo debugBuildInfo = new BuildInfo(BuildMode.debug, buildInfo.flavor,
         previewDart2: buildInfo.previewDart2,
+        trackWidgetCreation: buildInfo.trackWidgetCreation,
         extraFrontEndOptions: buildInfo.extraFrontEndOptions,
         extraGenSnapshotOptions: buildInfo.extraGenSnapshotOptions,
         preferSharedLibrary: buildInfo.preferSharedLibrary);

packages/flutter_tools/lib/src/ios/xcodeproj.dart

diff --git a/packages/flutter_tools/lib/src/ios/xcodeproj.dart b/packages/flutter_tools/lib/src/ios/xcodeproj.dart
index 38ba246..4dfd917 100644
--- a/packages/flutter_tools/lib/src/ios/xcodeproj.dart
+++ b/packages/flutter_tools/lib/src/ios/xcodeproj.dart
@@ -117,6 +117,10 @@
     localsBuffer.writeln('PREVIEW_DART_2=true');
   }
 
+  if (buildInfo.trackWidgetCreation) {
+    localsBuffer.writeln('TRACK_WIDGET_CREATION=true');
+  }
+
   final File localsFile = fs.file(_generatedXcodePropertiesPath(projectPath));
   localsFile.createSync(recursive: true);
   localsFile.writeAsStringSync(localsBuffer.toString());