[turbofan] Add basic support for calling to (a subset of) C functions.

test/unittests/compiler/raw-machine-assembler.h

Index: test/unittests/compiler/raw-machine-assembler.h
diff --git a/test/unittests/compiler/raw-machine-assembler.h b/test/unittests/compiler/raw-machine-assembler.h
index 45e1e3ec31e27d00b25d61b6ce93d8b69eab89bf..c35eecfaf238b29ce7240b843515772d26c62237 100644
--- a/test/unittests/compiler/raw-machine-assembler.h
+++ b/test/unittests/compiler/raw-machine-assembler.h
@@ -471,6 +471,15 @@ class RawMachineAssembler : public GraphBuilder {
   // Call to a runtime function with zero parameters.
   Node* CallRuntime1(Runtime::FunctionId function, Node* arg0, Node* context,
                      Node* frame_state);
+  // Call to a C function with zero parameters.
+  Node* CallCFunction0(MachineType return_type, Node* function);
+  // Call to a C function with one parameter.
+  Node* CallCFunction1(MachineType return_type, MachineType arg0_type,
+                       Node* function, Node* arg0);
+  // Call to a C function with two parameters.
+  Node* CallCFunction2(MachineType return_type, MachineType arg0_type,
+                       MachineType arg1_type, Node* function, Node* arg0,
+                       Node* arg1);
   void Return(Node* value);
   void Bind(Label* label);
   void Deoptimize(Node* state);