[turbofan] add ForTesting to pipeline entry points that are for testing only.

test/cctest/compiler/graph-builder-tester.cc

Index: test/cctest/compiler/graph-builder-tester.cc
diff --git a/test/cctest/compiler/graph-builder-tester.cc b/test/cctest/compiler/graph-builder-tester.cc
index 9c4379c52017be2388b22be4a4bd708a28d045cd..b0f470b01df6dd8efbf0edfa9d17c7d58c5607db 100644
--- a/test/cctest/compiler/graph-builder-tester.cc
+++ b/test/cctest/compiler/graph-builder-tester.cc
@@ -35,11 +35,9 @@ byte* MachineCallHelper::Generate() {
   if (!Pipeline::SupportedBackend()) return NULL;
   if (code_.is_null()) {
     Zone* zone = graph_->zone();
-    CompilationInfo info(zone->isolate(), zone);
-    Linkage linkage(zone,
-                    Linkage::GetSimplifiedCDescriptor(zone, machine_sig_));
-    Pipeline pipeline(&info);
-    code_ = pipeline.GenerateCodeForMachineGraph(&linkage, graph_);
+    CallDescriptor* desc =
+        Linkage::GetSimplifiedCDescriptor(zone, machine_sig_);
+    code_ = Pipeline::GenerateCodeForTesting(desc, graph_);
   }
   return code_.ToHandleChecked()->entry();
 }