feat(build): require parameter types

Fixes #2833

modules/angular2/src/http/backends/mock_backend.ts

@@ -90,7 +90,7 @@ export class MockConnection {
    * returned
    * from {@link Http}.
    */
-  mockError(err?) {
+  mockError(err?: Error) {
     // Matches XHR semantics
     this.readyState = ReadyStates.DONE;
     ObservableWrapper.callThrow(this.response, err);
@@ -185,8 +185,8 @@ export class MockBackend {
   constructor() {
     this.connectionsArray = [];
     this.connections = new EventEmitter();
-    ObservableWrapper.subscribe(this.connections,
-                                connection => this.connectionsArray.push(connection));
+    ObservableWrapper.subscribe<MockConnection>(
+        this.connections, connection => this.connectionsArray.push(connection));
     this.pendingConnections = new EventEmitter();
   }
 
@@ -207,7 +207,9 @@ export class MockBackend {
    *
    * This method only exists in the mock implementation, not in real Backends.
    */
-  resolveAllConnections() { ObservableWrapper.subscribe(this.connections, c => c.readyState = 4); }
+  resolveAllConnections() {
+    ObservableWrapper.subscribe<MockConnection>(this.connections, c => c.readyState = 4);
+  }
 
   /**
    * Creates a new {@link MockConnection}. This is equivalent to calling `new

modules/angular2/src/http/headers.ts

@@ -31,7 +31,7 @@ export class Headers {
     if (headers instanceof Headers) {
       this._headersMap = (<Headers>headers)._headersMap;
     } else if (headers instanceof StringMap) {
-      this._headersMap = MapWrapper.createFromStringMap(headers);
+      this._headersMap = MapWrapper.createFromStringMap<List<string>>(headers);
       MapWrapper.forEach(this._headersMap, (v, k) => {
         if (!isListLikeIterable(v)) {
           var list = [];

modules/angular2/src/http/url_search_params.ts

@@ -61,5 +61,5 @@ export class URLSearchParams {
     return ListWrapper.join(paramsList, '&');
   }
 
-  delete (param): void { MapWrapper.delete(this.paramsMap, param); }
+  delete (param: string): void { MapWrapper.delete(this.paramsMap, param); }
 }