InstanceOfStub incorrectly interprets the hole as a prototype.

src/mips64/code-stubs-mips64.cc

Index: src/mips64/code-stubs-mips64.cc
diff --git a/src/mips64/code-stubs-mips64.cc b/src/mips64/code-stubs-mips64.cc
index 3ac065cf8689cac410c0cdafcfe7e69c61898f39..d4878fde74803f2626990075f32b8a6849fbfb24 100644
--- a/src/mips64/code-stubs-mips64.cc
+++ b/src/mips64/code-stubs-mips64.cc
@@ -1499,8 +1499,12 @@ void InstanceOfStub::Generate(MacroAssembler* masm) {
   __ GetObjectType(function, function_map, scratch);
   __ Branch(&slow_case, ne, scratch, Operand(JS_FUNCTION_TYPE));
 
-  // Ensure that {function} has an instance prototype.
+  // Go to the runtime if the function is not a constructor.
   __ lbu(scratch, FieldMemOperand(function_map, Map::kBitFieldOffset));
+  __ And(at, scratch, Operand(1 << Map::kIsConstructor));
+  __ Branch(&slow_case, eq, at, Operand(zero_reg));
+
+  // Ensure that {function} has an instance prototype.
   __ And(at, scratch, Operand(1 << Map::kHasNonInstancePrototype));
   __ Branch(&slow_case, ne, at, Operand(zero_reg));