add debug driver destroy method

Android/doric/src/main/java/pub/doric/DoricContext.java

@@ -148,7 +148,7 @@ public class DoricContext {
         doricDebugDriver = new DoricDebugDriver(new IStatusCallback() {
             @Override
             public void start() {
-                isDebugging=true;
+                isDebugging = true;
                 callEntity(DoricConstant.DORIC_ENTITY_INIT, initParams);
                 callEntity(DoricConstant.DORIC_ENTITY_CREATE);
             }
@@ -156,6 +156,7 @@ public class DoricContext {
     }
 
     public void stopDebug() {
+        doricDebugDriver.destroy();
         isDebugging = false;
         callEntity(DoricConstant.DORIC_ENTITY_INIT, initParams);
         callEntity(DoricConstant.DORIC_ENTITY_CREATE);

Android/doric/src/main/java/pub/doric/DoricDebugDriver.java

@@ -126,4 +126,9 @@ public class DoricDebugDriver implements IDoricDriver {
     public DoricRegistry getRegistry() {
         return doricJSEngine.getRegistry();
     }
+
+    public void destroy() {
+        doricJSEngine.teardown();
+        mBridgeExecutor.shutdown();
+    }
 }

Android/doric/src/main/java/pub/doric/dev/DebugContextPanel.java

@@ -69,6 +69,7 @@ public class DebugContextPanel extends DialogFragment {
                     jsonObject.addProperty("projectHome", BuildConfig.PROJECT_HOME);
                     jsonObject.addProperty("source", doricContext.getSource().replace(".js", ".ts"));
                     Doric.sendDevCommand(IDevKit.Command.DEBUG, jsonObject);
+                    dismissAllowingStateLoss();
                 }
             });
 

Android/doric/src/main/java/pub/doric/engine/DoricJSEngine.java

@@ -170,6 +170,7 @@ public class DoricJSEngine implements Handler.Callback, DoricTimerExtension.Time
 
     public void teardown() {
         mDoricJSE.teardown();
+        mTimerExtension.teardown();
     }
 
     private void loadBuiltinJS(String assetName) {

Android/doric/src/main/java/pub/doric/extension/timer/DoricTimerExtension.java

@@ -69,6 +69,10 @@ public class DoricTimerExtension implements Handler.Callback {
         return true;
     }
 
+    public void teardown() {
+        mTimerHandler.removeCallbacksAndMessages(null);
+    }
+
     private class TimerInfo {
         long timerId;
         long time;