[559286] Refactoring the GEF DOT DotToggleCommentTest test cases.

- Modify the DotToggleCommentTest test cases to use the
org.eclipse.xtext.ui.testing.AbstractEditorTest base class
provided by the Xtext framework.

org.eclipse.gef.dot.tests/src/org/eclipse/gef/dot/tests/DotToggleCommentTest.xtend

@@ -11,14 +11,12 @@
  *******************************************************************************/
 package org.eclipse.gef.dot.tests
 
-import com.google.inject.Inject
 import org.eclipse.gef.dot.tests.ui.DotUiInjectorProvider
-import org.eclipse.xtext.junit4.ui.AbstractEditorTest
 import org.eclipse.xtext.testing.InjectWith
 import org.eclipse.xtext.testing.XtextRunner
 import org.eclipse.xtext.ui.XtextProjectHelper
 import org.eclipse.xtext.ui.editor.XtextEditor
-import org.eclipse.xtext.ui.editor.XtextEditorInfo
+import org.eclipse.xtext.ui.testing.AbstractEditorTest
 import org.junit.Test
 import org.junit.runner.RunWith
 
@@ -28,8 +26,6 @@ import static extension org.eclipse.xtext.ui.testing.util.IResourcesSetupUtil.ad
 @InjectWith(DotUiInjectorProvider)
 class DotToggleCommentTest extends AbstractEditorTest {
 
-	@Inject XtextEditorInfo xtextEditorInfo
-
 	@Test def toggling_comment_001() {
 		'''
 			graph {
@@ -137,8 +133,4 @@ class DotToggleCommentTest extends AbstractEditorTest {
 		val actualContent = editor.document.get
 		expectedContent.assertEquals(actualContent)
 	}
-
-	override protected getEditorId() {
-		xtextEditorInfo.editorId
-	}
 }