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

test/mjsunit/wasm/wasm-module-builder.js

Index: test/mjsunit/wasm/wasm-module-builder.js
diff --git a/test/mjsunit/wasm/wasm-module-builder.js b/test/mjsunit/wasm/wasm-module-builder.js
index 900198d7d03efbde455a06e63eb269a8e47bc9ce..93055c6a6d5fee92f64a89aef2b70b5566729a93 100644
--- a/test/mjsunit/wasm/wasm-module-builder.js
+++ b/test/mjsunit/wasm/wasm-module-builder.js
@@ -179,17 +179,13 @@ class WasmModuleBuilder {
     return func;
   }
 
-  addImportWithModule(module, name, type) {
+  addImport(module = "", name, type) {

[Clemens Hammacher, 2016/12/20 14:18:23]

Woot? What does this default argument do?

[titzer, 2016/12/20 14:23:35]

If the argument is undefined, it will be automatically converted to the default
value. It's most useful for parameters at the end of the list.

I've updated this and other methods to have a default module name of empty and
to check that the name is a string.

     let type_index = (typeof type) == "number" ? type : this.addType(type);
     this.imports.push({module: module, name: name, kind: kExternalFunction,
                        type: type_index});
     return this.num_imported_funcs++;
   }
 
-  addImport(name, type) {
-    return this.addImportWithModule(name, undefined, type);
-  }
-
   addImportedGlobal(module, name, type) {
     let o = {module: module, name: name, kind: kExternalGlobal, type: type,
              mutable: false}