refactor(compiler): set element attributes via one call

This makes the cost of using directives that have host attributes
smaller.

Part of #11683

modules/@angular/compiler/test/output/output_emitter_codegen_typed.ts

@@ -11,7 +11,7 @@
 import {TypeScriptEmitter} from '@angular/compiler/src/output/ts_emitter';
 
 import {print} from '../../src/facade/lang';
-import {assetUrl} from '../../src/util';
+import {assetUrl} from '../../src/identifiers';
 
 function unimplemented(): any {
   throw new Error('unimplemented');

modules/@angular/compiler/test/output/output_emitter_codegen_untyped.ts

@@ -10,7 +10,7 @@
 import {JavaScriptEmitter} from '@angular/compiler/src/output/js_emitter';
 
 import {print} from '../../src/facade/lang';
-import {assetUrl} from '../../src/util';
+import {assetUrl} from '../../src/identifiers';
 
 import {SimpleJsImportGenerator, codegenExportsVars, codegenStmts} from './output_emitter_util';
 

modules/@angular/compiler/test/output/output_emitter_util.ts

@@ -7,9 +7,9 @@
  */
 
 import {CompileIdentifierMetadata} from '@angular/compiler/src/compile_metadata';
+import {assetUrl} from '@angular/compiler/src/identifiers';
 import * as o from '@angular/compiler/src/output/output_ast';
 import {ImportGenerator} from '@angular/compiler/src/output/path_util';
-import {assetUrl} from '@angular/compiler/src/util';
 import {EventEmitter} from '@angular/core';
 import {BaseError} from '@angular/core/src/facade/errors';
 import {ViewType} from '@angular/core/src/linker/view_type';