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

src/v8.gyp

 # Copyright 2012 the V8 project authors. All rights reserved.
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 #       notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
 #       copyright notice, this list of conditions and the following
 #       disclaimer in the documentation and/or other materials provided
@@ skipping 1057 matching lines @@
         'lookup-cache-inl.h',
         'lookup-cache.cc',
         'lookup-cache.h',
         'lookup.cc',
         'lookup.h',
         'map-updater.cc',
         'map-updater.h',
         'macro-assembler.h',
         'machine-type.cc',
         'machine-type.h',
+        'managed.h',
         'messages.cc',
         'messages.h',
         'msan.h',
         'objects-body-descriptors-inl.h',
         'objects-body-descriptors.h',
         'objects-debug.cc',
         'objects-inl.h',
         'objects-printer.cc',
         'objects.cc',
         'objects.h',
@@ skipping 212 matching lines @@
         'vector.h',
         'version.cc',
         'version.h',
         'vm-state-inl.h',
         'vm-state.h',
         'wasm/decoder.h',
         'wasm/function-body-decoder.cc',
         'wasm/function-body-decoder.h',
         'wasm/function-body-decoder-impl.h',
         'wasm/leb-helper.h',
-        'wasm/managed.h',
         'wasm/module-decoder.cc',
         'wasm/module-decoder.h',
         'wasm/signature-map.cc',
         'wasm/signature-map.h',
         'wasm/wasm-debug.cc',
         'wasm/wasm-external-refs.cc',
         'wasm/wasm-external-refs.h',
         'wasm/wasm-js.cc',
         'wasm/wasm-js.h',
         'wasm/wasm-limits.h',
@@ skipping 1186 matching lines @@
       'conditions': [
         ['want_separate_host_toolset_mkpeephole==1', {
           'toolsets': ['host'],
         }, {
           'toolsets': ['target'],
         }],
       ],
     },
   ],
 }