ARM: build fix for r19380.

src/a64/code-stubs-a64.cc

Index: src/a64/code-stubs-a64.cc
diff --git a/src/a64/code-stubs-a64.cc b/src/a64/code-stubs-a64.cc
index 40aa0b617a4b5a625150126c4fe2cbae8a47bf68..50b8bb2852e042b74ff1efbebfe95736de92a0a5 100644
--- a/src/a64/code-stubs-a64.cc
+++ b/src/a64/code-stubs-a64.cc
@@ -5655,8 +5655,12 @@ 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);
 
   const int spill_offset = 1 + kApiStackSpace;