Use SubMonintor in TextChange

done() call not necessary here and convert can also handle null.

See https://www.eclipse.org/articles/Article-Progress-Monitors/article.html

bundles/org.eclipse.ltk.core.refactoring/src/org/eclipse/ltk/core/refactoring/TextChange.java

@@ -247,7 +247,6 @@ public Change perform(IProgressMonitor pm) throws CoreException {
 			throw Changes.asCoreException(e);
 		} finally {
 			releaseDocument(document, subMon.newChild(1));
-			subMon.done();
 		}
 	}
 
@@ -311,7 +310,6 @@ public IDocument getCurrentDocument(IProgressMonitor pm) throws CoreException {
 		} finally {
 			releaseDocument(result, subMon.newChild(1));
 		}
-		subMon.done();
 		return result;
 	}