MIPS: build fix for r19380

Port r19381 (5476e11b)

BUG=
R=plind44@gmail.com

Review URL: https://codereview.chromium.org/163953014

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@19395 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/mips/code-stubs-mips.cc

@@ -5708,8 +5708,12 @@ void CallApiFunctionStub::Generate(MacroAssembler* masm) {
   MemOperand context_restore_operand(
       fp, (2 + FCA::kContextSaveIndex) * kPointerSize);
   // Stores return the first js argument.
-  int return_value_offset =
-      2 + (is_store ? FCA::kArgsLength : FCA::kReturnValueOffset);
+  int return_value_offset = 0;
+  if (is_store) {
+    return_value_offset = 2 + FCA::kArgsLength;
+  } else {
+    return_value_offset = 2 + FCA::kReturnValueOffset;
+  }
   MemOperand return_value_operand(fp, return_value_offset * kPointerSize);
 
   __ CallApiFunctionAndReturn(api_function_address,