docs(di): add docs to Injector

Closes #4254

modules/angular2/test/core/di/injector_spec.ts

@@ -4,12 +4,10 @@ import {describe, ddescribe, it, iit, expect, beforeEach} from 'angular2/test_li
 import {SpyDependencyProvider} from '../spies';
 import {
   Injector,
-  ProtoInjector,
   bind,
   ResolvedBinding,
   Key,
   forwardRef,
-  DependencyMetadata,
   Injectable,
   InjectMetadata,
   SelfMetadata,
@@ -17,12 +15,17 @@ import {
   SkipSelfMetadata,
   Optional,
   Inject,
-  BindingWithVisibility,
-  Visibility,
   Binding
 } from 'angular2/core';
+import {DependencyMetadata} from 'angular2/src/core/di/metadata';
 
-import {InjectorInlineStrategy, InjectorDynamicStrategy} from 'angular2/src/core/di/injector';
+import {
+  InjectorInlineStrategy,
+  InjectorDynamicStrategy,
+  ProtoInjector,
+  BindingWithVisibility,
+  Visibility
+} from 'angular2/src/core/di/injector';
 
 class CustomDependencyMetadata extends DependencyMetadata {}
 

modules/angular2/test/public_api_spec.ts

@@ -115,9 +115,6 @@ const NG_API = [
   'BindingBuilder.toFactory',
   'BindingBuilder.toValue',
 
-  'BindingWithVisibility',
-  'BindingWithVisibility.getKeyId',
-
   'By',  // TODO: not sure
   'By.all',
   'By.css',
@@ -351,6 +348,9 @@ const NG_API = [
   'DebugElement.queryAll',
   'DebugElement.triggerEventHandler',
 
+  'DependencyMetadata',
+  'DependencyMetadata.token',
+
   'DecimalPipe',
   'DecimalPipe.constructor',
   'DecimalPipe.transform',
@@ -370,8 +370,6 @@ const NG_API = [
 
   'Dependency',
   'Dependency.fromKey',
-  'DependencyMetadata',
-  'DependencyMetadata.token',
 
   'Directive',
   'Directive.constructor',
@@ -750,9 +748,6 @@ const NG_API = [
 
   'PropertyMetadata',
 
-  'ProtoInjector',
-  'ProtoInjector.getBindingAtIndex',
-
   'ProtoViewRef',
 
   'Query',
@@ -979,8 +974,6 @@ const NG_API = [
   'ViewRef.renderFragment',
   'ViewRef.setLocal',
 
-  'Visibility',
-
   'WrappedException',
   'WrappedException.captureStackTrace',
   'WrappedException.constructor',