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/core/src/render/api.ts

@@ -61,8 +61,6 @@ export abstract class Renderer {
 
   abstract setElementClass(renderElement: any, className: string, isAdd: boolean);
 
-  abstract setElementStyles(renderElement: any, styles: {[key: string]: string});
-
   abstract setElementStyle(renderElement: any, styleName: string, styleValue: string);
 
   abstract invokeElementMethod(renderElement: any, methodName: string, args?: any[]);