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 bcedc07eb8a5d06f9ef781198b1384faf3e4b9cc..88e7e318e5e9851f54fa6ab72a4db2ca53eb0bb6 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; }
 };