TextEditor: get CompletionAssistProvider from editor.

And not from the global object pool. This way, the editors that have
different highlighters for various language dialects, or editors that
support multiple languages in a single editor, can decide themselves on
what CompletionAssistProvider to provide.

Change-Id: Ieebc4a8e7b3de6470fdb8103035aa3b8b2ba6598
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@digia.com>

src/plugins/glsleditor/glsleditor.cpp

@@ -207,6 +207,11 @@ bool GLSLEditorEditable::open(QString *errorString, const QString &fileName, con
     return b;
 }
 
+TextEditor::CompletionAssistProvider *GLSLEditorEditable::completionAssistProvider()
+{
+    return ExtensionSystem::PluginManager::getObject<GLSLCompletionAssistProvider>();
+}
+
 QString GLSLTextEditorWidget::wordUnderCursor() const
 {
     QTextCursor tc = textCursor();