[390501] org.eclipse.wst.dtd.ui.internal.style.LineStyleProviderForDTDSubSet never releases its unmanaged model
diff --git a/bundles/org.eclipse.wst.dtd.ui/src/org/eclipse/wst/dtd/ui/internal/style/LineStyleProviderForDTDSubSet.java b/bundles/org.eclipse.wst.dtd.ui/src/org/eclipse/wst/dtd/ui/internal/style/LineStyleProviderForDTDSubSet.java
index 0f25b7e..fd1783c 100644
--- a/bundles/org.eclipse.wst.dtd.ui/src/org/eclipse/wst/dtd/ui/internal/style/LineStyleProviderForDTDSubSet.java
+++ b/bundles/org.eclipse.wst.dtd.ui/src/org/eclipse/wst/dtd/ui/internal/style/LineStyleProviderForDTDSubSet.java
@@ -132,6 +132,10 @@
 		if (fInternalProvider != null) {
 			fInternalProvider.release();
 		}
+		if (fInternalModel != null) {
+			fInternalModel.releaseFromRead();
+			fInternalModel = null;
+		}
 	}
 
 	private void updateStyleRanges(IStructuredDocument document, String contents) {