PPC: Remove usages of Heap::NewSpaceStart and its external reference

src/ppc/macro-assembler-ppc.h

Index: src/ppc/macro-assembler-ppc.h
diff --git a/src/ppc/macro-assembler-ppc.h b/src/ppc/macro-assembler-ppc.h
index 0ba4e9da3dfa47503220f09798393844b65b828c..a529b627f27e17d17c07dde25ed409afab9c1cbc 100644
--- a/src/ppc/macro-assembler-ppc.h
+++ b/src/ppc/macro-assembler-ppc.h
@@ -1509,13 +1509,15 @@ class MacroAssembler : public Assembler {
   // If allocation info is present, condition flags are set to eq.
   void TestJSArrayForAllocationMemento(Register receiver_reg,
                                        Register scratch_reg,
+                                       Register scratch2_reg,
                                        Label* no_memento_found);
 
   void JumpIfJSArrayHasAllocationMemento(Register receiver_reg,
                                          Register scratch_reg,
+                                         Register scratch2_reg,
                                          Label* memento_found) {
     Label no_memento_found;
-    TestJSArrayForAllocationMemento(receiver_reg, scratch_reg,
+    TestJSArrayForAllocationMemento(receiver_reg, scratch_reg, scratch2_reg,
                                     &no_memento_found);
     beq(memento_found);
     bind(&no_memento_found);