Remove heap protection support.

src/platform.h

Index: src/platform.h
diff --git a/src/platform.h b/src/platform.h
index 06d3ca467618a17e1ac7a530b977aa32ffb030f0..9c3f90922daa0f4f274e813b76c793aafc880a9e 100644
--- a/src/platform.h
+++ b/src/platform.h
@@ -206,12 +206,6 @@ class OS {
   // Get the Alignment guaranteed by Allocate().
   static size_t AllocateAlignment();
 
-#ifdef ENABLE_HEAP_PROTECTION
-  // Protect/unprotect a block of memory by marking it read-only/writable.
-  static void Protect(void* address, size_t size);
-  static void Unprotect(void* address, size_t size, bool is_executable);
-#endif
-
   // 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