[wasm] asm.js - Remove Wasm.instantiateModuleFromAsm, use asm.js directly.

test/mjsunit/regress/regress-599717.js

 // Copyright 2016 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Flags: --expose-wasm
+// Flags: --validate-asm --allow-natives-syntax
 
 function __f_61(stdlib, foreign, buffer) {
   "use asm";
   var __v_14 = new stdlib.Float64Array(buffer);
   function __f_74() {
     var __v_35 = 6.0;
     __v_14[2] = __v_35 + 1.0;
   }
   return {__f_74: __f_74};
 }
 var ok = false;
 try {
   var __v_12 = new ArrayBuffer(2147483648);
   ok = true;
 } catch (e) {
   // Can happen on 32 bit systems.
 }
 if (ok) {
-  var module = Wasm.instantiateModuleFromAsm( __f_61.toString(), null, __v_12);
+  var module = __f_61(this, null, __v_12);
+  assertTrue(%IsAsmWasmCode(__f_61));
 }