[wasm] Add guard regions to end of WebAssembly.Memory buffers

src/base/platform/platform.h

Index: src/base/platform/platform.h
diff --git a/src/base/platform/platform.h b/src/base/platform/platform.h
index 5d570e7048b6d1fc4b600cfd3f9e38ba397e4a18..ce0ec510b8173eeb4eb70a22126edc8e69eb46cf 100644
--- a/src/base/platform/platform.h
+++ b/src/base/platform/platform.h
@@ -188,6 +188,9 @@ class V8_BASE_EXPORT OS {
   // Assign memory as a guard page so that access will cause an exception.
   static void Guard(void* address, const size_t size);
 
+  // Make a region of memory readable and writable.
+  static void Unprotect(void* address, const size_t size);
+
   // Generate a random address to be used for hinting mmap().
   static void* GetRandomMmapAddr();