[wasm] cleanup wasm-module.cc

- Coalesced all anonymous namespaces into one, and moved it to the
top of the file, to match elsewhere in the v8 codebase.
- Deleted dead code.
- Moved functions that turned out to be local to wasm-module.cc to
the anonymous namespace.

BUG=

Review-Url: https://codereview.chromium.org/2384183002
Cr-Commit-Position: refs/heads/master@{#39936}

src/frames.cc

@@ -1461,8 +1461,9 @@ Address WasmFrame::GetCallerStackPointer() const {
 }
 
 Object* WasmFrame::wasm_obj() const {
-  return wasm::GetOwningWasmInstance(*isolate()->factory()->undefined_value(),
-                                     LookupCode());
+  Object* ret = wasm::GetOwningWasmInstance(LookupCode());
+  if (ret == nullptr) ret = *(isolate()->factory()->undefined_value());
+  return ret;
 }
 
 uint32_t WasmFrame::function_index() const {

src/runtime/runtime-wasm.cc

@@ -32,10 +32,8 @@ RUNTIME_FUNCTION(Runtime_WasmGrowMemory) {
         Memory::Address_at(entry + StandardFrameConstants::kCallerPCOffset);
     Code* code =
         isolate->inner_pointer_to_code_cache()->GetCacheEntry(pc)->code;
-    Object* undefined = *isolate->factory()->undefined_value();
-    Object* owning_instance = wasm::GetOwningWasmInstance(undefined, code);
+    Object* owning_instance = wasm::GetOwningWasmInstance(code);
     CHECK_NOT_NULL(owning_instance);
-    CHECK_NE(owning_instance, undefined);
     module_instance = handle(JSObject::cast(owning_instance), isolate);
   }
 

src/wasm/wasm-module.h

@@ -321,7 +321,6 @@ struct ModuleEnv {
                                                          FunctionSig* sig);
   static compiler::CallDescriptor* GetI32WasmCallDescriptor(
       Zone* zone, compiler::CallDescriptor* descriptor);
-  compiler::CallDescriptor* GetCallDescriptor(Zone* zone, uint32_t index);
 };
 
 // A helper for printing out the names of functions.
@@ -510,10 +509,8 @@ uint32_t GetNumImportedFunctions(Handle<JSObject> wasm_object);
 
 // Assumed to be called with a code object associated to a wasm module instance.
 // Intended to be called from runtime functions.
-// Returns undefined if the runtime support was not setup, nullptr if the
-// instance
-// was collected, or the instance object owning the Code object
-Object* GetOwningWasmInstance(Object* undefined, Code* code);
+// Returns nullptr on failing to get owning instance.
+Object* GetOwningWasmInstance(Code* code);
 
 MaybeHandle<JSArrayBuffer> GetInstanceMemory(Isolate* isolate,
                                              Handle<JSObject> instance);