MIPS64 [turbofan]: Fix AssembleSwap for double stack slots.

TEST=mjsunit/compiler/regress-3, osr-maze1
BUG=

Review URL: https://codereview.chromium.org/1038173003

Cr-Commit-Position: refs/heads/master@{#27499}

src/compiler/mips/code-generator-mips.cc

@@ -1174,9 +1174,9 @@ void CodeGenerator::AssembleSwap(InstructionOperand* source,
     Register temp_0 = kScratchReg;
     FPURegister temp_1 = kScratchDoubleReg;
     MemOperand src0 = g.ToMemOperand(source);
-    MemOperand src1(src0.rm(), src0.offset() + kPointerSize);
+    MemOperand src1(src0.rm(), src0.offset() + kIntSize);
     MemOperand dst0 = g.ToMemOperand(destination);
-    MemOperand dst1(dst0.rm(), dst0.offset() + kPointerSize);
+    MemOperand dst1(dst0.rm(), dst0.offset() + kIntSize);
     __ ldc1(temp_1, dst0);  // Save destination in temp_1.
     __ lw(temp_0, src0);    // Then use temp_0 to copy source to destination.
     __ sw(temp_0, dst0);

src/compiler/mips64/code-generator-mips64.cc

@@ -1240,9 +1240,9 @@ void CodeGenerator::AssembleSwap(InstructionOperand* source,
     Register temp_0 = kScratchReg;
     FPURegister temp_1 = kScratchDoubleReg;
     MemOperand src0 = g.ToMemOperand(source);
-    MemOperand src1(src0.rm(), src0.offset() + kPointerSize);
+    MemOperand src1(src0.rm(), src0.offset() + kIntSize);
     MemOperand dst0 = g.ToMemOperand(destination);
-    MemOperand dst1(dst0.rm(), dst0.offset() + kPointerSize);
+    MemOperand dst1(dst0.rm(), dst0.offset() + kIntSize);
     __ ldc1(temp_1, dst0);  // Save destination in temp_1.
     __ lw(temp_0, src0);    // Then use temp_0 to copy source to destination.
     __ sw(temp_0, dst0);