require write action to commit non-physical documents

it was allowed to omit write action to prevent write-unsafe context warnings from completion & live templates, but those have been fixed in another way

platform/core-impl/src/com/intellij/psi/impl/DocumentCommitThread.java

@@ -696,7 +696,7 @@ public class DocumentCommitThread implements Runnable, Disposable, DocumentCommi
         return false; // optimistic locking failed
       }
 
-      if (file.isPhysical() && !ApplicationManager.getApplication().isWriteAccessAllowed()) {
+      if (!ApplicationManager.getApplication().isWriteAccessAllowed()) {
         VirtualFile vFile = viewProvider.getVirtualFile();
         LOG.error("Write action expected" +
                   "; document=" + document1 +

platform/core-impl/src/com/intellij/psi/impl/PsiDocumentManagerBase.java

@@ -454,12 +454,7 @@ public abstract class PsiDocumentManagerBase extends PsiDocumentManager implemen
       assert !isInUncommittedSet(document) : "Document :" + document;
     };
 
-    if (AbstractFileViewProvider.isFreeThreaded(psiFile.getViewProvider())) {
-      runnable.run();
-    }
-    else {
-      ApplicationManager.getApplication().runWriteAction(runnable);
-    }
+    ApplicationManager.getApplication().runWriteAction(runnable);
   }
 
   // true if the PSI is being modified and events being sent