PPC: Make --always-opt also optimize top-level code.

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 da3a84be128a093774990dcbb7b57304b8a2d212..c05a67704f0bb045af8989408a247ee1aa30eba1 100644
--- a/src/ppc/lithium-codegen-ppc.cc
+++ b/src/ppc/lithium-codegen-ppc.cc
@@ -182,6 +182,7 @@ bool LCodeGen::GeneratePrologue() {
     Comment(";;; Allocate local context");
     bool need_write_barrier = true;
     // Argument to NewContext is the function, which is in r4.
+    DCHECK(!info()->scope()->is_script_scope());
     if (heap_slots <= FastNewContextStub::kMaximumSlots) {
       FastNewContextStub stub(isolate(), heap_slots);
       __ CallStub(&stub);