Do not use runReadOnly during TypeHierarchyViewPart.updateViewers #1408

partial revert of fc6a25a

The used firePostSelectionChanged may run events that try to edit java
model.

fixes #1408

Since "Increase JavaModelCache #1929" its not a performance impact
anymore anyway, since the jdt.core typically keeps a cached JavaModel of
the TypeHierarchy after computing it anyway and does not need to compute
it in ui again.

org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/typehierarchy/TypeHierarchyLifeCycle.java

@@ -280,10 +280,8 @@ protected void doHierarchyRefreshBackground(final IJavaElement[] elements, final
 				}
 				if (pm.isCanceled())
 					return;
-				JavaCore.runReadOnly(() -> {
-					fTypeHierarchyViewPart.setViewersInput();
-					fTypeHierarchyViewPart.updateViewers();
-				});
+				fTypeHierarchyViewPart.setViewersInput();
+				fTypeHierarchyViewPart.updateViewers();
 			});
 		}
 	}