do not flag dead code if custom JUnit runner is used (IDEA-25444)

java/java-tests/testData/inspection/deadCode/enumInstantiation/ext_src/Test1.java

@@ -0,0 +1,7 @@
+public void Test1 {
+  void foo() {
+    if (Test.FIRST.invert() != Test.SECOND) {
+      //assert
+    }
+  }
+}