Fix MIPS build failures

For builtins-mips64.cc, add a static cast to resolve the ambiguity of "0"
around Operand(int64_t) and Operand(const char*).
For mips{,64}/macro-assembler-mips{,64}.cc, remove extra references to masm.

Change-Id: I9ce94c682c64b48501386029a912b0f5e32e268d
Reviewed-on: https://chromium-review.googlesource.com/c/1378365Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Commit-Queue: Taiju Tsuiki <tzik@chromium.org>
Cr-Commit-Position: refs/heads/master@{#58249}

src/mips/macro-assembler-mips.cc

@@ -4006,7 +4006,7 @@ void TurboAssembler::StoreReturnAddressAndCall(Register target) {
   // Set up sp in the delay slot.
   addiu(sp, sp, -kCArgsSlotsSize);
   // Make sure the stored 'ra' points to this position.
-  DCHECK_EQ(kNumInstructionsToJump, masm->InstructionsGeneratedSince(&find_ra));
+  DCHECK_EQ(kNumInstructionsToJump, InstructionsGeneratedSince(&find_ra));
 }
 
 void TurboAssembler::Ret(Condition cond, Register rs, const Operand& rt,

src/mips64/macro-assembler-mips64.cc

@@ -4337,7 +4337,7 @@ void TurboAssembler::StoreReturnAddressAndCall(Register target) {
   // Set up sp in the delay slot.
   daddiu(sp, sp, -kCArgsSlotsSize);
   // Make sure the stored 'ra' points to this position.
-  DCHECK_EQ(kNumInstructionsToJump, masm->InstructionsGeneratedSince(&find_ra));
+  DCHECK_EQ(kNumInstructionsToJump, InstructionsGeneratedSince(&find_ra));
 }
 
 void TurboAssembler::Ret(Condition cond, Register rs, const Operand& rt,