Desugar bitwise negation into XOR and kill all UnaryOp stuff.

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 8d533b36f409b0411a208e8d4f2d778c707dc06d..cb0896a8dedb16446c2f93304c7a1a2cbc14902b 100644
--- a/src/mips/assembler-mips.h
+++ b/src/mips/assembler-mips.h
@@ -358,6 +358,11 @@ class Operand BASE_EMBEDDED {
   // Return true if this is a register operand.
   INLINE(bool is_reg() const);
 
+  inline int32_t immediate() const {
+    ASSERT(!is_reg());
+    return imm32_;
+  }
+
   Register rm() const { return rm_; }
 
  private: