fix(di): do not use exceptions to detect if reflection is enabled

modules/angular2/src/reflection/platform_reflection_capabilities.ts

@@ -3,6 +3,7 @@ import {GetterFn, SetterFn, MethodFn} from './types';
 import {List} from 'angular2/src/facade/collection';
 
 export interface PlatformReflectionCapabilities {
+  isReflectionEnabled(): boolean;
   factory(type: Type): Function;
   interfaces(type: Type): List<any>;
   parameters(type: Type): List<List<any>>;

modules/angular2/src/reflection/reflection.dart

@@ -7,6 +7,10 @@ import 'platform_reflection_capabilities.dart';
 import 'package:angular2/src/facade/lang.dart';
 
 class NoReflectionCapabilities implements PlatformReflectionCapabilities {
+  bool isReflectionEnabled() {
+    return false;
+  }
+
   Function factory(Type type) {
     throw "Cannot find reflection information on ${stringify(type)}";
   }

modules/angular2/src/reflection/reflection_capabilities.dart

@@ -8,6 +8,10 @@ import 'platform_reflection_capabilities.dart';
 class ReflectionCapabilities implements PlatformReflectionCapabilities {
   ReflectionCapabilities([metadataReader]) {}
 
+  bool isReflectionEnabled() {
+    return true;
+  }
+
   Function factory(Type type) {
     ClassMirror classMirror = reflectType(type);
     MethodMirror ctor = classMirror.declarations[classMirror.simpleName];

modules/angular2/src/reflection/reflection_capabilities.ts

@@ -15,6 +15,8 @@ export class ReflectionCapabilities implements PlatformReflectionCapabilities {
 
   constructor(reflect?: any) { this._reflect = isPresent(reflect) ? reflect : global.Reflect; }
 
+  isReflectionEnabled(): boolean { return true; }
+
   factory(t: Type): Function {
     switch (t.length) {
       case 0:

modules/angular2/src/reflection/reflector.ts

@@ -27,6 +27,8 @@ export class Reflector {
     this.reflectionCapabilities = reflectionCapabilities;
   }
 
+  isReflectionEnabled(): boolean { return this.reflectionCapabilities.isReflectionEnabled(); }
+
   registerFunction(func: Function, funcInfo: StringMap<string, any>): void {
     this._injectableInfo.set(func, funcInfo);
   }