Remove --stop-at flag from several backends.

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

Index: src/crankshaft/mips/lithium-codegen-mips.cc
diff --git a/src/crankshaft/mips/lithium-codegen-mips.cc b/src/crankshaft/mips/lithium-codegen-mips.cc
index 7f14f1e23830c168a13ea1a2157bf07b818c85f2..6927818f9ae841724959d8322bdb9c9bd6bf95a4 100644
--- a/src/crankshaft/mips/lithium-codegen-mips.cc
+++ b/src/crankshaft/mips/lithium-codegen-mips.cc
@@ -127,13 +127,6 @@ 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
-
     // a1: Callee's JS function.
     // cp: Callee's context.
     // fp: Caller's frame pointer.