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

test/mjsunit/wasm/instantiate-module-basic.js

Index: test/mjsunit/wasm/instantiate-module-basic.js
diff --git a/test/mjsunit/wasm/instantiate-module-basic.js b/test/mjsunit/wasm/instantiate-module-basic.js
index d3a70dcda85d24a3a617bddffc8ae4222147a66f..c9c6e17f3555d0110aa0a85b23ff8adeed7b288a 100644
--- a/test/mjsunit/wasm/instantiate-module-basic.js
+++ b/test/mjsunit/wasm/instantiate-module-basic.js
@@ -120,8 +120,8 @@ assertFalse(WebAssembly.validate(bytes(88, 88, 88, 88, 88, 88, 88, 88)));
   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("m", "some_value", kSig_i_v);
+  builder.addImport("m", "writer", signature);
 
   builder.addFunction("main", kSig_i_i)
     .addBody([
@@ -155,10 +155,12 @@ assertFalse(WebAssembly.validate(bytes(88, 88, 88, 88, 88, 88, 88, 88)));
 
   var outval_1;
   var outval_2;
-  var i1 = new WebAssembly.Instance(module, {some_value: () => 1,
-                                    writer: (x)=>outval_1 = x }, mem_1);
-  var i2 = new WebAssembly.Instance(module, {some_value: () => 2,
-                                    writer: (x)=>outval_2 = x }, mem_2);
+  var i1 = new WebAssembly.Instance(module, {m: {some_value: () => 1,
+                                                 writer: (x)=>outval_1 = x }},
+                                    mem_1);
+  var i2 = new WebAssembly.Instance(module, {m: {some_value: () => 2,
+                                                 writer: (x)=>outval_2 = x }},
+                                    mem_2);
 
   assertEquals(43, i1.exports.main(0));
   assertEquals(1002, i2.exports.main(0));