PPC: [debugger] Remove code to predict step-in target.

Port 2f559f21

R=yangguo@chromium.org, joransiu@ca.ibm.com, jyan@ca.ibm.com, michael_dawson@ca.ibm.com
BUG=

Review URL: https://codereview.chromium.org/1490923004

Cr-Commit-Position: refs/heads/master@{#32482}

src/ppc/macro-assembler-ppc.cc

@@ -1089,12 +1089,12 @@ void MacroAssembler::FloodFunctionIfStepping(Register fun, Register new_target,
                                              const ParameterCount& expected,
                                              const ParameterCount& actual) {
   Label skip_flooding;
-  ExternalReference debug_step_action =
-      ExternalReference::debug_last_step_action_address(isolate());
-  mov(r7, Operand(debug_step_action));
+  ExternalReference step_in_enabled =
+      ExternalReference::debug_step_in_enabled_address(isolate());
+  mov(r7, Operand(step_in_enabled));
   lbz(r7, MemOperand(r7));
-  cmpi(r7, Operand(StepIn));
-  bne(&skip_flooding);
+  cmpi(r7, Operand::Zero());
+  beq(&skip_flooding);
   {
     FrameScope frame(this,
                      has_frame() ? StackFrame::NONE : StackFrame::INTERNAL);