Add ParameterMirror.isInitializingFormal to dart:mirrors

sdk/lib/_internal/js_runtime/lib/js_mirrors.dart

Index: sdk/lib/_internal/js_runtime/lib/js_mirrors.dart
diff --git a/sdk/lib/_internal/js_runtime/lib/js_mirrors.dart b/sdk/lib/_internal/js_runtime/lib/js_mirrors.dart
index aa836ca0baa45592736d39b2e0e4c2cee6b2a180..2ce78fc96bc9879660eb336f4e518c64351f23e5 100644
--- a/sdk/lib/_internal/js_runtime/lib/js_mirrors.dart
+++ b/sdk/lib/_internal/js_runtime/lib/js_mirrors.dart
@@ -1624,6 +1624,7 @@ class JsSyntheticSetterParameter implements ParameterMirror {
   bool get isFinal => true;
   bool get isPrivate => false;
   bool get hasDefaultValue => false;
+  bool get isInitializingFormal => false;
   InstanceMirror get defaultValue => null;
   List<InstanceMirror> get metadata => const [];
   SourceLocation get location => throw new UnimplementedError();
@@ -2411,6 +2412,10 @@ class JsMethodMirror extends JsDeclarationMirror implements MethodMirror {
         bool isNamed = info.areOptionalParametersNamed;
         for (JsParameterMirror parameter in type.parameters) {
           var name = info.parameterName(i);
+          bool isInitializingFormal = false;
+          if (isConstructor) {
+            isInitializingFormal = info.isFieldInitializerParameter(i);
+          }
           List<int> annotations = info.parameterMetadataAnnotations(i);
           var p;
           if (i < info.requiredParameterCount) {
@@ -2420,7 +2425,8 @@ class JsMethodMirror extends JsDeclarationMirror implements MethodMirror {
             var defaultValue = info.defaultValue(i);
             p = new JsParameterMirror(
                 name, this, parameter._type, metadataList: annotations,
-                isOptional: true, isNamed: isNamed, defaultValue: defaultValue);
+                isOptional: true, isNamed: isNamed, defaultValue: defaultValue,
+                isInitializingFormal: isInitializingFormal);
           }
           formals[i++] = p;
         }
@@ -2534,6 +2540,7 @@ class JsParameterMirror extends JsDeclarationMirror implements ParameterMirror {
                      {this.metadataList: const <int>[],
                      this.isOptional: false,
                      this.isNamed: false,
+                     this.isInitializingFormal: false,
                      defaultValue})
       : _defaultValue = defaultValue,
         super(s(unmangledName));
@@ -2553,6 +2560,8 @@ class JsParameterMirror extends JsDeclarationMirror implements ParameterMirror {
   // TODO(ahe): Implement this.
   bool get isConst => false;
 
+  final bool isInitializingFormal;
+
   bool get hasDefaultValue => _defaultValue != null;
 
   get defaultValue {