deps: backport a02d97e from v8 upstream

Original commit message:

  Fix --max_old_space_size=4096 integer overflow.

  BUG=v8:3857
  LOG=N

  Review URL: https://codereview.chromium.org/897543002

  Cr-Commit-Position: refs/heads/master@{#26510}

PR-URL: https://github.com/joyent/node/pull/9200
Reviewed-by: Trevor Norris <trev.norris@gmail.com>
Reviewed-by: Julien Gilli <julien.gilli@joyent.com>

deps/v8/src/heap/heap.cc

@@ -4828,10 +4828,10 @@ bool Heap::ConfigureHeap(int max_semi_space_size, int max_old_space_size,
     max_semi_space_size_ = max_semi_space_size * MB;
   }
   if (max_old_space_size > 0) {
-    max_old_generation_size_ = max_old_space_size * MB;
+    max_old_generation_size_ = static_cast<intptr_t>(max_old_space_size) * MB;
   }
   if (max_executable_size > 0) {
-    max_executable_size_ = max_executable_size * MB;
+    max_executable_size_ = static_cast<intptr_t>(max_executable_size) * MB;
   }
 
   // If max space size flags are specified overwrite the configuration.
@@ -4839,10 +4839,11 @@ bool Heap::ConfigureHeap(int max_semi_space_size, int max_old_space_size,
     max_semi_space_size_ = FLAG_max_semi_space_size * MB;
   }
   if (FLAG_max_old_space_size > 0) {
-    max_old_generation_size_ = FLAG_max_old_space_size * MB;
+    max_old_generation_size_ =
+        static_cast<intptr_t>(FLAG_max_old_space_size) * MB;
   }
   if (FLAG_max_executable_size > 0) {
-    max_executable_size_ = FLAG_max_executable_size * MB;
+    max_executable_size_ = static_cast<intptr_t>(FLAG_max_executable_size) * MB;
   }
 
   if (FLAG_stress_compaction) {