PPC: Turn StoreIC::Megamorphic into a builtin, get rid of the non-monomorphic-cache

Port 79ff6507

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

Review URL: https://codereview.chromium.org/1874983004

Cr-Commit-Position: refs/heads/master@{#35405}

src/ic/ppc/ic-ppc.cc

@@ -750,8 +750,8 @@ void StoreIC::GenerateMegamorphic(MacroAssembler* masm) {
   Code::Flags flags =
       Code::RemoveHolderFromFlags(Code::ComputeHandlerFlags(Code::STORE_IC));
 
-  masm->isolate()->stub_cache()->GenerateProbe(masm, Code::STORE_IC, flags,
-                                               receiver, name, r6, r7, r8, r9);
+  masm->isolate()->stub_cache()->GenerateProbe(
+      masm, Code::STORE_IC, flags, receiver, name, r8, r9, r10, r11);
 
   // Cache miss: Jump to runtime.
   GenerateMiss(masm);