Landing: Write protect executable pages in the VM.

runtime/vm/assembler_mips.cc

Index: runtime/vm/assembler_mips.cc
diff --git a/runtime/vm/assembler_mips.cc b/runtime/vm/assembler_mips.cc
index 7d17451848606518922917df93dfce375124c071..004107fba9b538ff7d0b4486828758eb57a06232 100644
--- a/runtime/vm/assembler_mips.cc
+++ b/runtime/vm/assembler_mips.cc
@@ -106,6 +106,8 @@ class PatchFarJump : public AssemblerFixup {
     // the far branch with a near one, and so these instructions should be NOPs.
     ASSERT((high == Instr::kNopInstruction) && (low == Instr::kNopInstruction));
   }
+
+  virtual bool IsPointerOffset() const { return false; }
 };