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

test/mjsunit/wasm/data-segments.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
 
 load("test/mjsunit/wasm/wasm-constants.js");
 load("test/mjsunit/wasm/wasm-module-builder.js");
 
 var debug = false;
@@ skipping 21 matching lines @@
 SimpleDataSegmentTest(12);
 SimpleDataSegmentTest(1064);
 
 function GlobalImportedInitTest(pad) {
   print("GlobaleImportedInitTest(" + pad + ")...");
   var builder = new WasmModuleBuilder();
   builder.addMemory(1, 1, false);
 
   while (pad-- > 0) builder.addGlobal(kAstI32);  // pad
 
-  var g = builder.addImportedGlobal("offset", undefined, kAstI32);
+  var g = builder.addImportedGlobal("mod", "offset", kAstI32);
 
   while (pad-- > 0) builder.addGlobal(kAstI32);  // pad
 
   builder.addFunction("load", kSig_i_i)
     .addBody([kExprGetLocal, 0, kExprI32LoadMem, 0, 0])
     .exportAs("load");
   builder.addDataSegment(g.index, [5, 5, 5, 5], true);
 
   var buffer = builder.toBuffer(debug);
   var module = new WebAssembly.Module(buffer);
 
   for (var offset of [0, 12, 192, 1024]) {
-    var instance = new WebAssembly.Instance(module, {offset: offset});
+    var instance = new WebAssembly.Instance(module, {mod: {offset: offset}});
     for (var i = offset - 20; i < offset + 20; i += 4) {
       if (i < 0) continue;
       var expected = i == offset ? 84215045 : 0;
       assertEquals(expected, instance.exports.load(i));
     }
   }
 }
 
 GlobalImportedInitTest(0);
 GlobalImportedInitTest(1);
 GlobalImportedInitTest(4);