feat(TestBed): add whitespace handling to compile

Add whitespace handling to the TestBed’s compile function.

Closes #1262. Previously, strings passed with leading or trailing
whitespace would be compiled incorrectly. Now, valid HTML with
arbitrary whitespace in and surrounding it can be compiled properly.

Author: Jare Fagbemi

lib/mock/test_bed.dart

@@ -54,12 +54,22 @@ class TestBed {
     return rootElement;
   }
 
+  String _handleWhitespace(html) {
+    return html
+        .split('\n')
+        .map((line) {
+          var trimmed = line.trim();
+          return trimmed +
+              (trimmed.isEmpty || trimmed.endsWith('>') ? '' : ' ');
+        })
+        .join();
+  }
   /**
    * Convert an [html] String to a [List] of [Element]s.
    */
   List<Element> toNodeList(html) {
     var div = new DivElement();
-    var sanitizedHtml = html.split('\n').map((line) => line.trim()).join(' ');
+    var sanitizedHtml = _handleWhitespace(html);
     div.setInnerHtml(sanitizedHtml, treeSanitizer: new NullTreeSanitizer());
     var nodes = [];
     for (var node in div.nodes) {

test/mock/test_bed_spec.dart

@@ -27,6 +27,24 @@ void main() {
       expect(directiveInst.destroyed).toBe(true);
     });
 
+    it('should handle whitespace cleanly', () {
+      var root = _.compile('''
+        <div>
+          <h1
+             attr="Hi">
+          </h1>
+        </div>
+      <span  
+       attr2="Bye"
+
+      ></span>
+      ''');
+
+      expect(root.runtimeType).toBe(DivElement);
+      expect(_.rootElements[1].runtimeType).toBe(SpanElement);
+      expect(_.rootElements.length).toBe(2);
+    });
+
   });
 }