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

test/mjsunit/wasm/gc-frame.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 --expose-gc
 
 load("test/mjsunit/wasm/wasm-constants.js");
 load("test/mjsunit/wasm/wasm-module-builder.js");
 
 function makeFFI(func, t) {
   var builder = new WasmModuleBuilder();
 
   var sig_index = builder.addType(makeSig([t,t,t,t,t,t,t,t,t,t], [t]));
-  builder.addImport("func", sig_index);
+  builder.addImport("m", "func", sig_index);
   // Try to create a frame with lots of spilled values and parameters
   // on the stack to try to catch GC bugs in the reference maps for
   // the different parts of the stack.
   builder.addFunction("main", sig_index)
     .addBody([
       kExprGetLocal, 0,         // --
       kExprGetLocal, 1,         // --
       kExprGetLocal, 2,         // --
       kExprGetLocal, 3,         // --
       kExprGetLocal, 4,         // --
@@ skipping 11 matching lines @@
       kExprGetLocal, 4,         // --
       kExprGetLocal, 5,         // --
       kExprGetLocal, 6,         // --
       kExprGetLocal, 7,         // --
       kExprGetLocal, 8,         // --
       kExprGetLocal, 9,         // --
       kExprCallFunction, 0,    // --
     ])                          // --
     .exportFunc();
 
-  return builder.instantiate({func: func}).exports.main;
+  return builder.instantiate({m: {func: func}}).exports.main;
 }
 
 
 function print10(a, b, c, d, e, f, g, h, i) {
   print(a + ",", b + ",", c + ",", d + ",", e + ",", f + ",", g + ",", h + ",", i);
   gc();
   print(a + ",", b + ",", c + ",", d + ",", e + ",", f + ",", g + ",", h + ",", i);
 }
 
 (function I32Test() {
@@ skipping 32 matching lines @@
   var gc_object = {
       valueOf: function() {
         // Call the GC in valueOf, which is called within the JSToWasm wrapper.
         gc();
         return {};
       }
   };
 
   main(gc_object);
 })();