[turbofan] Remove the JSGraph dependency from the ControlFlowOptimizer.

test/unittests/compiler/graph-unittest.cc

Index: test/unittests/compiler/graph-unittest.cc
diff --git a/test/unittests/compiler/graph-unittest.cc b/test/unittests/compiler/graph-unittest.cc
index ff2af9ce35fa2e1f88d2b0b0e5da5ff2dceab5a6..d2ab3c3a2652c843bd527dc0861b9c8e7a2b9eae 100644
--- a/test/unittests/compiler/graph-unittest.cc
+++ b/test/unittests/compiler/graph-unittest.cc
@@ -81,6 +81,16 @@ Node* GraphTest::UndefinedConstant() {
 }
 
 
+Node* GraphTest::EmptyFrameState() {
+  Node* state_values = graph()->NewNode(common()->StateValues(0));
+  return graph()->NewNode(
+      common()->FrameState(JS_FRAME, BailoutId::None(),
+                           OutputFrameStateCombine::Ignore()),
+      state_values, state_values, state_values, NumberConstant(0),
+      UndefinedConstant(), graph()->start());
+}
+
+
 Matcher<Node*> GraphTest::IsFalseConstant() {
   return IsHeapConstant(
       Unique<HeapObject>::CreateImmovable(factory()->false_value()));