Remove --stop-at flag from several backends.

src/crankshaft/ppc/lithium-codegen-ppc.cc

Index: src/crankshaft/ppc/lithium-codegen-ppc.cc
diff --git a/src/crankshaft/ppc/lithium-codegen-ppc.cc b/src/crankshaft/ppc/lithium-codegen-ppc.cc
index 1134ebf0edbaf23735dd1c86db4452539e56e9c7..4452bbbf9d865b96c225bb00b5bfca5b1a440d1f 100644
--- a/src/crankshaft/ppc/lithium-codegen-ppc.cc
+++ b/src/crankshaft/ppc/lithium-codegen-ppc.cc
@@ -104,13 +104,6 @@ bool LCodeGen::GeneratePrologue() {
   if (info()->IsOptimizing()) {
     ProfileEntryHookStub::MaybeCallEntryHook(masm_);
 
-#ifdef DEBUG
-    if (strlen(FLAG_stop_at) > 0 &&
-        info_->literal()->name()->IsUtf8EqualTo(CStrVector(FLAG_stop_at))) {
-      __ stop("stop_at");
-    }
-#endif
-
     // r4: Callee's JS function.
     // cp: Callee's context.
     // pp: Callee's constant pool pointer (if enabled)