[wasm] Implement correct 2-level namespace for imports.

test/mjsunit/wasm/compiled-module-serialization.js

 // Copyright 2015 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 --allow-natives-syntax --expose-gc
 
 load("test/mjsunit/wasm/wasm-constants.js");
 load("test/mjsunit/wasm/wasm-module-builder.js");
 
 (function SerializeAndDeserializeModule() {
   var builder = new WasmModuleBuilder();
   builder.addMemory(1,1, true);
   var kSig_v_i = makeSig([kAstI32], []);
   var signature = builder.addType(kSig_v_i);
-  builder.addImport("some_value", kSig_i_v);
-  builder.addImport("writer", signature);
+  builder.addImport("", "some_value", kSig_i_v);
+  builder.addImport("", "writer", signature);
 
   builder.addFunction("main", kSig_i_i)
     .addBody([
       kExprGetLocal, 0,
       kExprI32LoadMem, 0, 0,
       kExprI32Const, 1,
       kExprCallIndirect, signature, kTableZero,
       kExprGetLocal,0,
       kExprI32LoadMem,0, 0,
       kExprCallFunction, 0,
@@ skipping 14 matching lines @@
   module = null;
   gc();
   module = %DeserializeWasmModule(buff, wire_bytes);
 
   var mem_1 = new WebAssembly.Memory({initial: 1});
   var view_1 = new Int32Array(mem_1.buffer);
 
   view_1[0] = 42;
 
   var outval_1;
-  var i1 = new WebAssembly.Instance(module, {some_value: () => 1,
-                                    writer: (x)=>outval_1 = x }, mem_1);
+  var i1 = new WebAssembly.Instance(module, {"": {some_value: () => 1,
+                                                  writer: (x)=>outval_1 = x }}, mem_1);
 
   assertEquals(43, i1.exports.main(0));
 
   assertEquals(42, outval_1);
 })();
 
 (function DeserializeInvalidObject() {
   var invalid_buffer = new ArrayBuffer(10);
 
   module = %DeserializeWasmModule(invalid_buffer, invalid_buffer);
@@ skipping 30 matching lines @@
   var serialized = %SerializeWasmModule(compiled_module);
   var clone = %DeserializeWasmModule(serialized, wire_bytes);
 
   assertNotNull(clone);
   assertFalse(clone == undefined);
   assertFalse(clone == compiled_module);
   assertEquals(clone.constructor, compiled_module.constructor);
   var instance3 = new WebAssembly.Instance(clone);
   assertFalse(instance3 == undefined);
 })();