feat(dart/transform): Use the best available Change Detectors

Enable pregenerated (for Dart) and JIT (for Js) change detectors when
possible. Previously we would always use `DynamicChangeDetector`s, but
these cause megamorphic calls and are therefore much slower.

Closes #502

modules/angular2/src/transform/common/directive_metadata_reader.dart

@@ -88,20 +88,20 @@ class _DirectiveMetadataVisitor extends Object
   }
 
   DirectiveMetadata get meta => DirectiveMetadata.create(
-    type: _type,
-    selector: _selector,
-    compileChildren: _compileChildren,
-    properties: _properties,
-    host: _host,
-    readAttributes: _readAttributes,
-    exportAs: _exportAs,
-    callOnDestroy: _callOnDestroy,
-    callOnChange: _callOnChange,
-    callOnCheck: _callOnCheck,
-    callOnInit: _callOnInit,
-    callOnAllChangesDone: _callOnAllChangesDone,
-    changeDetection: _changeDetection,
-    events: _events);
+      type: _type,
+      selector: _selector,
+      compileChildren: _compileChildren,
+      properties: _properties,
+      host: _host,
+      readAttributes: _readAttributes,
+      exportAs: _exportAs,
+      callOnDestroy: _callOnDestroy,
+      callOnChange: _callOnChange,
+      callOnCheck: _callOnCheck,
+      callOnInit: _callOnInit,
+      callOnAllChangesDone: _callOnAllChangesDone,
+      changeDetection: _changeDetection,
+      events: _events);
 
   @override
   Object visitAnnotation(Annotation node) {

modules/angular2/src/transform/common/options.dart

@@ -8,6 +8,9 @@ const DEFAULT_OPTIMIZATION_PHASES = 5;
 
 const CUSTOM_ANNOTATIONS_PARAM = 'custom_annotations';
 const ENTRY_POINT_PARAM = 'entry_points';
+const GENERATE_CHANGE_DETECTORS_PARAM = 'generate_change_detectors';
+const INIT_REFLECTOR_PARAM = 'init_reflector';
+const MIRROR_MODE_PARAM = 'mirror_mode';
 const OPTIMIZATION_PHASES_PARAM = 'optimization_phases';
 const REFLECTION_ENTRY_POINT_PARAM = 'reflection_entry_points';
 
@@ -32,6 +35,9 @@ class TransformerOptions {
   /// The [AnnotationMatcher] which is used to identify angular annotations.
   final AnnotationMatcher annotationMatcher;
 
+  /// Whether to create change detector classes for discovered `@View`s.
+  final bool generateChangeDetectors;
+
   /// The number of phases to spend optimizing output size.
   /// Each additional phase adds time to the transformation but may decrease
   /// final output size. There is a limit beyond which this will no longer
@@ -43,13 +49,15 @@ class TransformerOptions {
 
   TransformerOptions._internal(this.entryPoints, this.reflectionEntryPoints,
       this.modeName, this.mirrorMode, this.initReflector,
-      this.annotationMatcher, this.optimizationPhases);
+      this.annotationMatcher, this.optimizationPhases,
+      this.generateChangeDetectors);
 
   factory TransformerOptions(List<String> entryPoints,
       {List<String> reflectionEntryPoints, String modeName: 'release',
       MirrorMode mirrorMode: MirrorMode.none, bool initReflector: true,
       List<AnnotationDescriptor> customAnnotationDescriptors: const [],
-      int optimizationPhases: DEFAULT_OPTIMIZATION_PHASES}) {
+      int optimizationPhases: DEFAULT_OPTIMIZATION_PHASES,
+      bool generateChangeDetectors: true}) {
     if (reflectionEntryPoints == null || reflectionEntryPoints.isEmpty) {
       reflectionEntryPoints = entryPoints;
     }
@@ -58,6 +66,6 @@ class TransformerOptions {
     optimizationPhases = optimizationPhases.isNegative ? 0 : optimizationPhases;
     return new TransformerOptions._internal(entryPoints, reflectionEntryPoints,
         modeName, mirrorMode, initReflector, annotationMatcher,
-        optimizationPhases);
+        optimizationPhases, generateChangeDetectors);
   }
 }

modules/angular2/src/transform/common/options_reader.dart

@@ -10,10 +10,12 @@ TransformerOptions parseBarbackSettings(BarbackSettings settings) {
   var entryPoints = _readFileList(config, ENTRY_POINT_PARAM);
   var reflectionEntryPoints =
       _readFileList(config, REFLECTION_ENTRY_POINT_PARAM);
-  var initReflector = !config.containsKey('init_reflector') ||
-      config['init_reflector'] != false;
+  var initReflector =
+      _readBool(config, INIT_REFLECTOR_PARAM, defaultValue: true);
+  var generateChangeDetectors =
+      _readBool(config, GENERATE_CHANGE_DETECTORS_PARAM, defaultValue: true);
   String mirrorModeVal =
-      config.containsKey('mirror_mode') ? config['mirror_mode'] : '';
+      config.containsKey(MIRROR_MODE_PARAM) ? config[MIRROR_MODE_PARAM] : '';
   var mirrorMode = MirrorMode.none;
   switch (mirrorModeVal) {
     case 'debug':
@@ -34,7 +36,14 @@ TransformerOptions parseBarbackSettings(BarbackSettings settings) {
       mirrorMode: mirrorMode,
       initReflector: initReflector,
       customAnnotationDescriptors: _readCustomAnnotations(config),
-      optimizationPhases: optimizationPhases);
+      optimizationPhases: optimizationPhases,
+      generateChangeDetectors: generateChangeDetectors);
+}
+
+bool _readBool(Map config, String paramName, {bool defaultValue}) {
+  return config.containsKey(paramName)
+      ? config[paramName] != false
+      : defaultValue;
 }
 
 /// Cribbed from the polymer project.