fix(transformer): Fix string interpolation for bindings.

Previously it did not stringify properties and used `+` instead of ` `.

modules/angular2/test/transform/integration/two_annotations_files/bar.dart

@@ -4,7 +4,9 @@ import 'package:angular2/src/core/annotations_impl/annotations.dart';
 import 'package:angular2/src/core/annotations_impl/view.dart';
 
 @Component(selector: '[soup]')
-@View(template: 'Salad')
+@View(template: 'Salad: {{myNum}} is awesome')
 class MyComponent {
+  int myNum;
+
   MyComponent();
 }

modules/angular2/test/transform/integration/two_annotations_files/expected/bar.ng_deps.dart

@@ -17,9 +17,11 @@ void initReflector(reflector) {
       'parameters': const [],
       'annotations': const [
         const Component(selector: '[soup]'),
-        const View(template: 'Salad')
+        const View(template: 'Salad: {{myNum}} is awesome')
       ]
-    });
+    })
+    ..registerGetters({'myNum': (o) => o.myNum})
+    ..registerSetters({'myNum': (o, v) => o.myNum = v});
   _gen.preGeneratedProtoDetectors['MyComponent_comp_0'] =
       _MyComponent_ChangeDetector0.newProtoChangeDetector;
 }
@@ -31,6 +33,8 @@ class _MyComponent_ChangeDetector0 extends _gen.AbstractChangeDetector {
   dynamic _locals = null;
   dynamic _alreadyChecked = false;
   MyComponent _context = null;
+  dynamic _myNum0 = _gen.ChangeDetectionUtil.uninitialized();
+  dynamic _interpolate1 = _gen.ChangeDetectionUtil.uninitialized();
 
   _MyComponent_ChangeDetector0(this._dispatcher, this._pipeRegistry,
       this._protos, this._directiveRecords)
@@ -41,12 +45,44 @@ class _MyComponent_ChangeDetector0 extends _gen.AbstractChangeDetector {
       _gen.ChangeDetectionUtil.throwDehydrated();
     }
     var context = null;
+    var myNum0 = null;
+    var interpolate1 = null;
     var change_context = false;
+    var change_myNum0 = false;
+    var change_interpolate1 = false;
     var isChanged = false;
     var currentProto;
     var changes = null;
 
     context = _context;
+    currentProto = _protos[0];
+    myNum0 = context.myNum;
+    if (!_gen.looseIdentical(myNum0, _myNum0)) {
+      change_myNum0 = true;
+
+      _myNum0 = myNum0;
+    }
+    if (change_myNum0) {
+      currentProto = _protos[1];
+      interpolate1 = "Salad: " "${myNum0 == null ? "" : myNum0}" " is awesome";
+      if (!_gen.looseIdentical(interpolate1, _interpolate1)) {
+        change_interpolate1 = true;
+        if (throwOnChange) {
+          _gen.ChangeDetectionUtil.throwOnChange(currentProto,
+              _gen.ChangeDetectionUtil.simpleChange(
+                  _interpolate1, interpolate1));
+        }
+
+        _dispatcher.notifyOnBinding(currentProto.bindingRecord, interpolate1);
+
+        _interpolate1 = interpolate1;
+      }
+    } else {
+      interpolate1 = _interpolate1;
+    }
+    changes = null;
+
+    isChanged = false;
 
     _alreadyChecked = true;
   }
@@ -65,6 +101,8 @@ class _MyComponent_ChangeDetector0 extends _gen.AbstractChangeDetector {
 
   void dehydrate() {
     _context = null;
+    _myNum0 = _gen.ChangeDetectionUtil.uninitialized();
+    _interpolate1 = _gen.ChangeDetectionUtil.uninitialized();
     _locals = null;
   }