Fix --max_old_space_size=4096 integer overflow.

src/heap/heap.cc

Index: src/heap/heap.cc
diff --git a/src/heap/heap.cc b/src/heap/heap.cc
index 52bd70a7527afdd53eac21a8288d01e9966a56f2..b247ff8018444e7bc750c2cb5d88ff8eee71902d 100644
--- a/src/heap/heap.cc
+++ b/src/heap/heap.cc
@@ -5108,10 +5108,10 @@ 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.
@@ -5119,10 +5119,11 @@ 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) {