Write protect executable pages in the VM.

runtime/vm/assembler_arm.h

Index: runtime/vm/assembler_arm.h
diff --git a/runtime/vm/assembler_arm.h b/runtime/vm/assembler_arm.h
index c5971e5b2c14db0c4a275decd4a43c7f3d1ca52c..fb1fc1481cfe88ded802912f98f886e6c873d362 100644
--- a/runtime/vm/assembler_arm.h
+++ b/runtime/vm/assembler_arm.h
@@ -313,6 +313,11 @@ class Assembler : public ValueObject {
   // Misc. functionality
   intptr_t CodeSize() const { return buffer_.Size(); }
   intptr_t prologue_offset() const { return prologue_offset_; }
+
+  // Count the fixups that produce a pointer offset, without processing
+  // the fixups.  On ARM there are no pointers in code.
+  intptr_t CountPointerOffsets() const { return 0; }
+
   const ZoneGrowableArray<intptr_t>& GetPointerOffsets() const {
     ASSERT(buffer_.pointer_offsets().length() == 0);  // No pointers in code.
     return buffer_.pointer_offsets();