PPC: [compiler] Remove broken support for undetectable strings.

src/ppc/lithium-codegen-ppc.cc

Index: src/ppc/lithium-codegen-ppc.cc
diff --git a/src/ppc/lithium-codegen-ppc.cc b/src/ppc/lithium-codegen-ppc.cc
index 75023a2c415a11cfb0270dc8e78fb13d829fca6f..1e28f664458dfccc9352e91064204f8d9e50f371 100644
--- a/src/ppc/lithium-codegen-ppc.cc
+++ b/src/ppc/lithium-codegen-ppc.cc
@@ -5903,11 +5903,7 @@ Condition LCodeGen::EmitTypeofIs(Label* true_label, Label* false_label,
   } else if (String::Equals(type_name, factory->string_string())) {
     __ JumpIfSmi(input, false_label);
     __ CompareObjectType(input, scratch, no_reg, FIRST_NONSTRING_TYPE);
-    __ bge(false_label);
-    __ lbz(scratch, FieldMemOperand(scratch, Map::kBitFieldOffset));
-    __ ExtractBit(r0, scratch, Map::kIsUndetectable);
-    __ cmpi(r0, Operand::Zero());
-    final_branch_condition = eq;
+    final_branch_condition = lt;
 
   } else if (String::Equals(type_name, factory->symbol_string())) {
     __ JumpIfSmi(input, false_label);