fix(renderer): remove unecessary setElementStyles method

There is no need to expose this additional method inside of the Renderer
API. The functionality can be restored by looping and calling
`setElementStyle` instead.

Note that this change is changing code that was was introduced after
the last release therefore this fix is not a breaking change.

Closes #9000
Closes #9009

modules/@angular/platform-browser/src/dom/dom_renderer.ts

@@ -228,11 +228,6 @@ export class DomRenderer implements Renderer {
     }
   }
 
-  setElementStyles(renderElement: any, styles: {[key: string]: string}) {
-    StringMapWrapper.forEach(styles,
-                             (value, prop) => this.setElementStyle(renderElement, prop, value));
-  }
-
   setElementStyle(renderElement: any, styleName: string, styleValue: string): void {
     if (isPresent(styleValue)) {
       getDOM().setStyle(renderElement, styleName, stringify(styleValue));