Additional improvements for PT-140709005

For missing properties in toplevel nodes, place the error marker at the
end of the document.

vscode-extensions/vscode-concourse/src/test/java/org/springframework/ide/vscode/concourse/ConcourseEditorTest.java

@@ -2268,7 +2268,10 @@ public class ConcourseEditorTest {
 		editor = harness.newEditor(LanguageIds.CONCOURSE_TASK,
 				"image: some-image"
 		);
-		editor.assertProblems("image: some-image|[platform, run] are required");
+		List<Diagnostic> problems = editor.assertProblems("|[platform, run] are required");
+		for (Diagnostic p : problems) {
+			editor.assertIsEndOfFile(p.getRange());
+		}
 
 		editor = harness.newEditor(LanguageIds.CONCOURSE_TASK,
 				"platform: a-platform\n" +