[turbofan] Add CalleeSavedFPRegisters to CallDescriptor.

src/compiler/ppc/linkage-ppc.cc

Index: src/compiler/ppc/linkage-ppc.cc
diff --git a/src/compiler/ppc/linkage-ppc.cc b/src/compiler/ppc/linkage-ppc.cc
index 39ebb63efa3b59a7dccac5b604521809606d2f3b..0674237736dce6f300307ee1386d190e20c4ba11 100644
--- a/src/compiler/ppc/linkage-ppc.cc
+++ b/src/compiler/ppc/linkage-ppc.cc
@@ -25,6 +25,10 @@ struct PPCLinkageHelperTraits {
            r24.bit() | r25.bit() | r26.bit() | r27.bit() | r28.bit() |
            r29.bit() | r30.bit() | fp.bit();
   }
+  static RegList CCalleeSaveFPURegisters() {
+    // TODO(palfia): finish.

[paul.l..., 2015/06/15 23:05:17]

I think the ppc callee saved are d14-d31.However, I have doubt, as they are not
saved in JSEntryStub.

[akos.palfi.imgtec, 2015/06/22 17:33:20]

Acknowledged.

+    return 0;
+  }
   static Register CRegisterParameter(int i) {
     static Register register_parameters[] = {r3, r4, r5, r6, r7, r8, r9, r10};
     return register_parameters[i];