Merge r10809 into 3.7 branch

src/platform.h

Index: src/platform.h
===================================================================
--- src/platform.h	(revision 10867)
+++ src/platform.h	(working copy)
@@ -184,6 +184,8 @@
   // Get the Alignment guaranteed by Allocate().
   static size_t AllocateAlignment();
 
+  static intptr_t CommitPageSize();
+
   // Returns an indication of whether a pointer is in a space that
   // has been allocated by Allocate().  This method may conservatively
   // always return false, but giving more accurate information may
@@ -352,6 +354,9 @@
   // Uncommit real memory.  Returns whether the operation succeeded.
   bool Uncommit(void* address, size_t size);
 
+  // Creates a single guard page at the given address.
+  bool Guard(void* address);
+
   void Release() {
     ASSERT(IsReserved());
     // Notice: Order is important here. The VirtualMemory object might live