Implement Instance instances correctly; fix a few error cases

src/wasm/wasm-js.h

Index: src/wasm/wasm-js.h
diff --git a/src/wasm/wasm-js.h b/src/wasm/wasm-js.h
index f5b9596ee23603fada919b3c3161bc8ef8788ec1..c70082fa5c18b871c9698568d37d255f2b4388f5 100644
--- a/src/wasm/wasm-js.h
+++ b/src/wasm/wasm-js.h
@@ -13,16 +13,7 @@ namespace internal {
 // Exposes a WASM API to JavaScript through the V8 API.
 class WasmJs {
  public:
-  static void Install(Isolate* isolate, Handle<JSGlobalObject> global_object);
-
-  V8_EXPORT_PRIVATE static void InstallWasmModuleSymbolIfNeeded(
-      Isolate* isolate, Handle<JSGlobalObject> global, Handle<Context> context);
-
-  V8_EXPORT_PRIVATE static void InstallWasmMapsIfNeeded(
-      Isolate* isolate, Handle<Context> context);
-  static void InstallWasmConstructors(Isolate* isolate,
-                                      Handle<JSGlobalObject> global,
-                                      Handle<Context> context);
+  static void Install(Isolate* isolate);
 
   // WebAssembly.Table.
   static bool IsWasmTableObject(Isolate* isolate, Handle<Object> value);