fix(projection): allow more bound render elements than app elements.

Fixes #3236
Closes #3247

modules/angular2/src/render/api.ts

@@ -307,6 +307,10 @@ export class RenderProtoViewMergeMapping {
               // Mappings of nested ProtoViews are in depth first order, with all
               // indices for one ProtoView in a consecuitve block.
               public mappedElementIndices: number[],
+              // Number of bound render element.
+              // Note: This could be more than the original ones
+              // as we might have bound a new element for projecting bound text nodes.
+              public mappedElementCount: number,
               // Mapping from app text index to render text index.
               // Mappings of nested ProtoViews are in depth first order, with all
               // indices for one ProtoView in a consecuitve block.

modules/angular2/src/render/dom/view/proto_view_merger.ts

@@ -56,9 +56,10 @@ export function mergeProtoViewsRecursively(protoViewRefs: List<RenderProtoViewRe
   var mergedProtoView =
       DomProtoView.create(mainProtoView.original.type, rootElement, fragmentsRootNodeCount,
                           rootTextNodeIndices, mergedElementBinders);
-  return new RenderProtoViewMergeMapping(
-      new DomProtoViewRef(mergedProtoView), fragmentsRootNodeCount.length, mappedElementIndices,
-      mappedTextIndices, hostElementIndicesByViewIndex, nestedViewCounts);
+  return new RenderProtoViewMergeMapping(new DomProtoViewRef(mergedProtoView),
+                                         fragmentsRootNodeCount.length, mappedElementIndices,
+                                         mergedBoundElements.length, mappedTextIndices,
+                                         hostElementIndicesByViewIndex, nestedViewCounts);
 }
 
 function cloneProtoViews(protoViewRefs: List<RenderProtoViewRef | List<any>>,