feat(http): serialize search parameters from request options

- Extends URLSearchParams API to include operations for combining
  different URLSearchParams objects:

  These new methods include:
  setAll(otherParams): performs `this.set(key, values[0])` for each
      key/value-list pair in `otherParams`

  appendAll(otherParams): performs `this.append(key, values)` for
      each key/value-list pair in `otherParams`

  replaceAll(otherParams): for each key/value-list pair in
      `otherParams`, replaces current set of values for `key` with
      a copy of the list of values.

- RequestOptions do not merge search params automatically (because
  there are multiple ways to do this). Instead, they replace any
  existing `search` field if `search` is provided. Explicit merging
  is required if merging is desirable.

- Some extra test coverage added.

Closes #2417
Closes #3020

modules/angular2/test/http/http_spec.ts

@@ -21,6 +21,7 @@ import {ResponseOptions} from 'angular2/src/http/base_response_options';
 import {Request} from 'angular2/src/http/static_request';
 import {EventEmitter, ObservableWrapper} from 'angular2/src/facade/async';
 import {ConnectionBackend} from 'angular2/src/http/interfaces';
+import {URLSearchParams} from 'angular2/src/http/url_search_params';
 
 class SpyObserver extends SpyObject {
   onNext: Function;
@@ -202,6 +203,47 @@ export function main() {
              ObservableWrapper.subscribe(http.head(url), res => {});
            }));
       });
+
+
+      describe('searchParams', () => {
+        it('should append search params to url', inject([AsyncTestCompleter], async => {
+             var params = new URLSearchParams();
+             params.append('q', 'puppies');
+             ObservableWrapper.subscribe<MockConnection>(backend.connections, c => {
+               expect(c.request.url).toEqual('https://www.google.com?q=puppies');
+               backend.resolveAllConnections();
+               async.done();
+             });
+             ObservableWrapper.subscribe(
+                 http.get('https://www.google.com', new RequestOptions({search: params})),
+                 res => {});
+           }));
+
+
+        it('should append string search params to url', inject([AsyncTestCompleter], async => {
+             ObservableWrapper.subscribe<MockConnection>(backend.connections, c => {
+               expect(c.request.url).toEqual('https://www.google.com?q=piggies');
+               backend.resolveAllConnections();
+               async.done();
+             });
+             ObservableWrapper.subscribe(
+                 http.get('https://www.google.com', new RequestOptions({search: 'q=piggies'})),
+                 res => {});
+           }));
+
+
+        it('should produce valid url when url already contains a query',
+           inject([AsyncTestCompleter], async => {
+             ObservableWrapper.subscribe<MockConnection>(backend.connections, c => {
+               expect(c.request.url).toEqual('https://www.google.com?q=angular&as_eq=1.x');
+               backend.resolveAllConnections();
+               async.done();
+             });
+             ObservableWrapper.subscribe(http.get('https://www.google.com?q=angular',
+                                                  new RequestOptions({search: 'as_eq=1.x'})),
+                                         res => {});
+           }));
+      });
     });
   });
 }

modules/angular2/test/http/url_search_params_spec.ts

@@ -30,6 +30,51 @@ export function main() {
       expect(searchParams.toString()).toEqual("q=URLUtils.searchParams&topic=api&topic=webdev");
       searchParams.delete("topic");
       expect(searchParams.toString()).toEqual("q=URLUtils.searchParams");
+
+      // Test default constructor
+      expect(new URLSearchParams().toString()).toBe("");
+    });
+
+
+    it('should support map-like merging operation via setAll()', () => {
+      var mapA = new URLSearchParams('a=1&a=2&a=3&c=8');
+      var mapB = new URLSearchParams('a=4&a=5&a=6&b=7');
+      mapA.setAll(mapB);
+      expect(mapA.has('a')).toBe(true);
+      expect(mapA.has('b')).toBe(true);
+      expect(mapA.has('c')).toBe(true);
+      expect(mapA.getAll('a')).toEqual(['4']);
+      expect(mapA.getAll('b')).toEqual(['7']);
+      expect(mapA.getAll('c')).toEqual(['8']);
+      expect(mapA.toString()).toEqual('a=4&c=8&b=7');
+    });
+
+
+    it('should support multimap-like merging operation via appendAll()', () => {
+      var mapA = new URLSearchParams('a=1&a=2&a=3&c=8');
+      var mapB = new URLSearchParams('a=4&a=5&a=6&b=7');
+      mapA.appendAll(mapB);
+      expect(mapA.has('a')).toBe(true);
+      expect(mapA.has('b')).toBe(true);
+      expect(mapA.has('c')).toBe(true);
+      expect(mapA.getAll('a')).toEqual(['1', '2', '3', '4', '5', '6']);
+      expect(mapA.getAll('b')).toEqual(['7']);
+      expect(mapA.getAll('c')).toEqual(['8']);
+      expect(mapA.toString()).toEqual('a=1&a=2&a=3&a=4&a=5&a=6&c=8&b=7');
+    });
+
+
+    it('should support multimap-like merging operation via replaceAll()', () => {
+      var mapA = new URLSearchParams('a=1&a=2&a=3&c=8');
+      var mapB = new URLSearchParams('a=4&a=5&a=6&b=7');
+      mapA.replaceAll(mapB);
+      expect(mapA.has('a')).toBe(true);
+      expect(mapA.has('b')).toBe(true);
+      expect(mapA.has('c')).toBe(true);
+      expect(mapA.getAll('a')).toEqual(['4', '5', '6']);
+      expect(mapA.getAll('b')).toEqual(['7']);
+      expect(mapA.getAll('c')).toEqual(['8']);
+      expect(mapA.toString()).toEqual('a=4&a=5&a=6&c=8&b=7');
     });
   });
 }