Core: Make IEditor::id a value member and adjust users

Change-Id: I47e457c4a1821c515cd8a740d27bfe005a0c09e6
Reviewed-by: Orgad Shaneh <orgads@gmail.com>
Reviewed-by: Eike Ziller <eike.ziller@digia.com>

src/plugins/android/javaeditor.cpp

@@ -52,6 +52,7 @@ using namespace Android::Internal;
 JavaEditor::JavaEditor(JavaEditorWidget *editor)
   : BaseTextEditor(editor)
 {
+    setId(Constants::JAVA_EDITOR_ID);
     setContext(Core::Context(Constants::C_JAVA_EDITOR,
               TextEditor::Constants::C_TEXTEDITOR));
 }
@@ -64,11 +65,6 @@ Core::IEditor *JavaEditor::duplicate()
     return ret->editor();
 }
 
-Core::Id JavaEditor::id() const
-{
-    return Core::Id(Constants::JAVA_EDITOR_ID);
-}
-
 TextEditor::CompletionAssistProvider *JavaEditor::completionAssistProvider()
 {
     return ExtensionSystem::PluginManager::getObject<JavaCompletionAssistProvider>();