Refactor ChangeLowering class to avoid template specialization.

test/compiler-unittests/compiler-unittests.cc

Index: test/compiler-unittests/compiler-unittests.cc
diff --git a/test/compiler-unittests/compiler-unittests.cc b/test/compiler-unittests/compiler-unittests.cc
index 2ce4c93ee220dfe735113300f6f14532a1b1c2e9..86d12400135b3a84f259d594121e174b3a35d10f 100644
--- a/test/compiler-unittests/compiler-unittests.cc
+++ b/test/compiler-unittests/compiler-unittests.cc
@@ -3,6 +3,7 @@
 // found in the LICENSE file.
 
 #include "include/libplatform/libplatform.h"
+#include "src/isolate-inl.h"
 #include "test/compiler-unittests/compiler-unittests.h"
 #include "testing/gmock/include/gmock/gmock.h"
 
@@ -27,6 +28,9 @@ CompilerTest::CompilerTest()
 CompilerTest::~CompilerTest() {}
 
 
+Factory* CompilerTest::factory() const { return isolate()->factory(); }
+
+
 // static
 void CompilerTest::SetUpTestCase() {
   Test::SetUpTestCase();