deps: cherry-pick 9a49b22 from V8 upstream

Original commit message:
  Fix alloc/dealloc size mismatch for v8::BackingStore

  On newer compilers the {operator delete} with explicit {size_t}
  argument would be instantiated for {v8::BackingStore} and used
  in the destructor of {std::unique_ptr<v8::BackingStore>}. The {size_t}
  argument is wrong though, since the pointer actually points
  to a {v8::internal::BackingStore} object.
  The solution is to explicitly provide a {operator delete}, preventing
  an implicitly generated {size_t} operator.

  Bug:v8:11081

  Change-Id: Iee0aa47a67f0e41000bea628942f7e3d70198b83
  Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2506712
  Commit-Queue: Ulan Degenbaev <[email protected]>
  Reviewed-by: Camillo Bruni <[email protected]>
  Cr-Commit-Position: refs/heads/master@{#70916}

PR-URL: nodejs#35939
Fixes: nodejs#35669
Refs: v8/v8@9a49b22
Reviewed-By: Jiawen Geng <[email protected]>
Reviewed-By: Michaël Zasso <[email protected]>
Reviewed-By: Richard Lau <[email protected]>
Reviewed-By: Rich Trott <[email protected]>
Reviewed-By: Colin Ihrig <[email protected]>
Reviewed-By: Gus Caplan <[email protected]>

common.gypi

@@ -36,7 +36,7 @@
 
     # Reset this number to 0 on major V8 upgrades.
     # Increment by one for each non-official patch applied to deps/v8.
-    'v8_embedder_string': '-node.14',
+    'v8_embedder_string': '-node.15',
 
     ##### V8 defaults for Node.js #####
 

deps/v8/include/v8.h

@@ -5054,6 +5054,13 @@ class V8_EXPORT BackingStore : public v8::internal::BackingStoreBase {
    */
   bool IsShared() const;
 
+  /**
+   * Prevent implicit instantiation of operator delete with size_t argument.
+   * The size_t argument would be incorrect because ptr points to the
+   * internal BackingStore object.
+   */
+  void operator delete(void* ptr) { ::operator delete(ptr); }
+
   /**
    * Wrapper around ArrayBuffer::Allocator::Reallocate that preserves IsShared.
    * Assumes that the backing_store was allocated by the ArrayBuffer allocator