[wasm] Cleanup unneeded casts to WasmInstanceObject

src/runtime/runtime-wasm.cc

Index: src/runtime/runtime-wasm.cc
diff --git a/src/runtime/runtime-wasm.cc b/src/runtime/runtime-wasm.cc
index 950c2dc8ede2f811d6669614d207aeeb28757030..46782cf575c1971bda284c87771f0a2017029948 100644
--- a/src/runtime/runtime-wasm.cc
+++ b/src/runtime/runtime-wasm.cc
@@ -20,23 +20,25 @@
 namespace v8 {
 namespace internal {
 
+namespace {
+Handle<WasmInstanceObject> GetWasmInstanceOnStackTop(Isolate* isolate) {
+  DisallowHeapAllocation no_allocation;
+  const Address entry = Isolate::c_entry_fp(isolate->thread_local_top());
+  Address pc =
+      Memory::Address_at(entry + StandardFrameConstants::kCallerPCOffset);
+  Code* code = isolate->inner_pointer_to_code_cache()->GetCacheEntry(pc)->code;
+  DCHECK_EQ(Code::WASM_FUNCTION, code->kind());
+  WasmInstanceObject* owning_instance = wasm::GetOwningWasmInstance(code);
+  CHECK_NOT_NULL(owning_instance);
+  return handle(owning_instance, isolate);
+}
+}  // namespace
+
 RUNTIME_FUNCTION(Runtime_WasmMemorySize) {
   HandleScope scope(isolate);
   DCHECK_EQ(0, args.length());
 
-  Handle<WasmInstanceObject> instance;
-  {
-    // Get the module JSObject
-    DisallowHeapAllocation no_allocation;
-    const Address entry = Isolate::c_entry_fp(isolate->thread_local_top());
-    Address pc =
-        Memory::Address_at(entry + StandardFrameConstants::kCallerPCOffset);
-    Code* code =
-        isolate->inner_pointer_to_code_cache()->GetCacheEntry(pc)->code;
-    WasmInstanceObject* owning_instance = wasm::GetOwningWasmInstance(code);
-    CHECK_NOT_NULL(owning_instance);
-    instance = handle(owning_instance, isolate);
-  }
+  Handle<WasmInstanceObject> instance = GetWasmInstanceOnStackTop(isolate);
   return *isolate->factory()->NewNumberFromInt(
       wasm::GetInstanceMemorySize(isolate, instance));
 }
@@ -45,19 +47,7 @@ RUNTIME_FUNCTION(Runtime_WasmGrowMemory) {
   HandleScope scope(isolate);
   DCHECK_EQ(1, args.length());
   CONVERT_UINT32_ARG_CHECKED(delta_pages, 0);
-  Handle<WasmInstanceObject> instance;
-  {
-    // Get the module JSObject
-    DisallowHeapAllocation no_allocation;
-    const Address entry = Isolate::c_entry_fp(isolate->thread_local_top());
-    Address pc =
-        Memory::Address_at(entry + StandardFrameConstants::kCallerPCOffset);
-    Code* code =
-        isolate->inner_pointer_to_code_cache()->GetCacheEntry(pc)->code;
-    WasmInstanceObject* owning_instance = wasm::GetOwningWasmInstance(code);
-    CHECK_NOT_NULL(owning_instance);
-    instance = handle(owning_instance, isolate);
-  }
+  Handle<WasmInstanceObject> instance = GetWasmInstanceOnStackTop(isolate);
   return *isolate->factory()->NewNumberFromInt(
       wasm::GrowMemory(isolate, instance, delta_pages));
 }