Fix uninitialized new.target register in InvokeBuiltin.

src/mips/macro-assembler-mips.cc

Index: src/mips/macro-assembler-mips.cc
diff --git a/src/mips/macro-assembler-mips.cc b/src/mips/macro-assembler-mips.cc
index 667a74a7a070c75920920ee23f3a36e9223a5915..8eb26256d308dde7cf9b3d5fbb8ed9b69a141a5e 100644
--- a/src/mips/macro-assembler-mips.cc
+++ b/src/mips/macro-assembler-mips.cc
@@ -4502,6 +4502,9 @@ void MacroAssembler::InvokeBuiltin(int native_context_index, InvokeFlag flag,
   // You can't call a builtin without a valid frame.
   DCHECK(flag == JUMP_FUNCTION || has_frame());
 
+  // Always initialize new target.
+  LoadRoot(a3, Heap::kUndefinedValueRootIndex);
+
   LoadNativeContextSlot(native_context_index, a1);
   lw(t9, FieldMemOperand(a1, JSFunction::kCodeEntryOffset));
   if (flag == CALL_FUNCTION) {