fix(compiler): create literal property bindings for empty *… directives.

Closes #4916

modules/angular2/src/core/compiler/template_parser.ts

@@ -272,6 +272,7 @@ class TemplateParseVisitor implements HtmlAstVisitor {
                                  targetMatchableAttrs, targetProps);
         } else {
           targetMatchableAttrs.push([dashCaseKey, '']);
+          this._parseLiteralAttr(dashCaseKey, null, attr.sourceInfo, targetProps);
         }
       }
       return true;