Fix some users of removed mirror API.

sdk/lib/_internal/dartdoc/lib/universe_serializer.dart

Index: sdk/lib/_internal/dartdoc/lib/universe_serializer.dart
diff --git a/sdk/lib/_internal/dartdoc/lib/universe_serializer.dart b/sdk/lib/_internal/dartdoc/lib/universe_serializer.dart
index ba57411423e135d15c2f361a40f7304c9b14e84a..fc1b0aa78352c6a8c9382cfa7e4f57bb719d662c 100755
--- a/sdk/lib/_internal/dartdoc/lib/universe_serializer.dart
+++ b/sdk/lib/_internal/dartdoc/lib/universe_serializer.dart
@@ -312,23 +312,35 @@ class ClassElement extends Element {
       this.interfaces.add(_optionalReference(interface));
     }
 
-    mirror.methods.forEach((childName, childMirror) {
+    mirror.declarations.values
+        .where((d) => d is MethodMirror))
+        .forEach((childMirror) {
       if (!childMirror.isConstructor && !childMirror.isGetter) {
+        var childName = childMirror.simpleName;
         addChild(new MethodElement(childName, childMirror, lookupMdnComment));
       }
     });
 
-    mirror.getters.forEach((childName, childMirror) {
+    mirror.declarations.values
+        .where((d) => d is MethodMirror && d.isGetter))
+        .forEach((childMirror) {
+      var childName = childMirror.simpleName;
       addChild(new GetterElement(childName, childMirror, lookupMdnComment));
     });
 
-    mirror.variables.forEach((childName, childMirror) {
-        addChild(new VariableElement(childName, childMirror,
-            lookupMdnComment));
+    mirror.declarations.values
+        .where((d) => d is VariableMirror))
+        .forEach((childMirror) {
+      var childName = childMirror.simpleName;
+      addChild(new VariableElement(childName, childMirror,
+          lookupMdnComment));
     });
 
-    mirror.constructors.forEach((constructorName, methodMirror) {
-      addChild(new MethodElement(constructorName, methodMirror,
+    mirror.declarations.values
+        .where((d) => d is MethodMirror && d.isConstructor))
+        .forEach((childMirror) {
+      var childName = childMirror.simpleName;
+      addChild(new MethodElement(childName, methodMirror,
           lookupMdnComment, 'constructor'));
     });