MIPS: Add code again to allow reclaiming old unexecuted functions.

src/mips/assembler-mips.h

Index: src/mips/assembler-mips.h
diff --git a/src/mips/assembler-mips.h b/src/mips/assembler-mips.h
index fd2ff0daa2804c3abd1d21caa84d15dd8070ccd6..db797ce9dc7b2c1a5f791dd2c0716712627fbb29 100644
--- a/src/mips/assembler-mips.h
+++ b/src/mips/assembler-mips.h
@@ -663,7 +663,9 @@ class Assembler : public AssemblerBase {
     PROPERTY_ACCESS_INLINED_CONTEXT_DONT_DELETE,
     // Helper values.
     LAST_CODE_MARKER,
-    FIRST_IC_MARKER = PROPERTY_ACCESS_INLINED
+    FIRST_IC_MARKER = PROPERTY_ACCESS_INLINED,
+    // Code aging
+    CODE_AGE_MARKER_NOP = 6
   };
 
   // Type == 0 is the default non-marking nop. For mips this is a