[wasm] Managed<T> ensures T's lifetime does not leak past Isolate's

src/wasm/wasm-objects.cc

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/wasm/wasm-objects.h"
 #include "src/utils.h"
 
 #include "src/base/iterator.h"
 #include "src/debug/debug-interface.h"
 #include "src/wasm/module-decoder.h"
@@ skipping 512 matching lines @@
     return false;
   return true;
 }
 
 WasmSharedModuleData* WasmSharedModuleData::cast(Object* object) {
   DCHECK(IsWasmSharedModuleData(object));
   return reinterpret_cast<WasmSharedModuleData*>(object);
 }
 
 wasm::WasmModule* WasmSharedModuleData::module() {
-  return reinterpret_cast<WasmModuleWrapper*>(get(kModuleWrapper))->get();
+  // We populate the kModuleWrapper field with a Foreign holding the
+  // address to the address of a WasmModule. This is because we can
+  // handle both cases when the WasmModule's lifetime is managed through
+  // a Managed<WasmModule> object, as well as cases when it's managed
+  // by the embedder. CcTests fall into the latter case.
+  return *(reinterpret_cast<wasm::WasmModule**>(
+      Foreign::cast(get(kModuleWrapper))->foreign_address()));
 }
 
 DEFINE_OPTIONAL_ARR_ACCESSORS(WasmSharedModuleData, module_bytes, kModuleBytes,
                               SeqOneByteString);
 DEFINE_ARR_GETTER(WasmSharedModuleData, script, kScript, Script);
 DEFINE_OPTIONAL_ARR_ACCESSORS(WasmSharedModuleData, asm_js_offset_table,
                               kAsmJsOffsetTable, ByteArray);
 DEFINE_OPTIONAL_ARR_GETTER(WasmSharedModuleData, breakpoint_infos,
                            kBreakPointInfos, FixedArray);
 
@@ skipping 634 matching lines @@
       !array->get(kPreviousInstanceWrapper)->IsFixedArray())
     return false;
   return true;
 }
 
 void WasmInstanceWrapper::set_instance_object(Handle<JSObject> instance,
                                               Isolate* isolate) {
   Handle<WeakCell> cell = isolate->factory()->NewWeakCell(instance);
   set(kWrapperInstanceObject, *cell);
 }