PPC: InstanceOfStub incorrectly interprets the hole as a prototype.

src/ppc/code-stubs-ppc.cc

Index: src/ppc/code-stubs-ppc.cc
diff --git a/src/ppc/code-stubs-ppc.cc b/src/ppc/code-stubs-ppc.cc
index b194258da641a41b0c9489696cec145686735c5d..d89bbd1e9620ef245b79418ac47f5619a3fca9a3 100644
--- a/src/ppc/code-stubs-ppc.cc
+++ b/src/ppc/code-stubs-ppc.cc
@@ -1421,8 +1421,12 @@ void InstanceOfStub::Generate(MacroAssembler* masm) {
   __ CompareObjectType(function, function_map, scratch, JS_FUNCTION_TYPE);
   __ bne(&slow_case);
 
-  // Ensure that {function} has an instance prototype.
+  // Go to the runtime if the function is not a constructor.
   __ lbz(scratch, FieldMemOperand(function_map, Map::kBitFieldOffset));
+  __ TestBit(scratch, Map::kIsConstructor, r0);
+  __ beq(&slow_case, cr0);
+
+  // Ensure that {function} has an instance prototype.
   __ TestBit(scratch, Map::kHasNonInstancePrototype, r0);
   __ bne(&slow_case, cr0);