Textinput: Only _destroy() clear button when present

(cherry picked from commit c6ba792)

Closes gh-7568
Fixes gh-7567

Author: Gabriel Schulhof

js/widgets/forms/clearButton.js

@@ -127,7 +127,9 @@ define( [
 
 		_destroy: function() {
 			this._super();
-			this._destroyClear();
+			if ( this.options.clearBtn ) {
+				this._destroyClear();
+			}
 		}
 
 	});

tests/unit/textinput/index.html

@@ -8,6 +8,7 @@
 	<script src="../../../external/requirejs/require.js"></script>
 	<script src="../../../js/requirejs.config.js"></script>
 	<script src="../../../js/jquery.tag.inserter.js"></script>
+	<script src="../../jquery.setNameSpace.js"></script>
 	<script src="../../../external/qunit/qunit.js"></script>
 	<script src="../../../tests/jquery.testHelper.js"></script>
 	<script src="../../../tests/jquery.setNameSpace.js"></script>
@@ -70,6 +71,9 @@
 		<input type="text" id="focus-class-test-for-input"></input>
 		<textarea id="focus-class-test-for-textarea"></textarea>
 		<input id="injection-test" data-nstest-clear-btn="true" data-nstest-clear-btn-text="'>a<script>$.clearBtnTextScriptInjected = true;</script>bc</a><a'">
+		<div id="destroy-test-container">
+			<input type="text" id="destroy-test" data-nstest-role="none"></input>
+		</div>
 	</div>
 </body>
 </html>

tests/unit/textinput/textinput_core.js

@@ -171,4 +171,14 @@
 			"no script was injected via clearBtnText option" );
 	});
 
+	test( "textinput is destroyed correctly", function() {
+		var originalDOM = $( "#destroy-test-container" ).clone(),
+			entry = $( "#destroy-test" );
+
+		entry.textinput().textinput( "destroy" );
+
+		deepEqual( $.testHelper.domEqual( originalDOM, $( "#destroy-test-container" ) ), true,
+			"Original DOM is restored after textinput destruction" );
+	});
+
 })(jQuery);