回滚master上关于map参数的设定，master上使用dynamic做为map的key，但在闲鱼环境中因为legacy code都是用String，所以为了适配而回滚

example/lib/simple_page_widgets.dart

@@ -42,7 +42,7 @@ class FirstRouteWidget extends StatelessWidget {
                   child: Text('Present second route'),
                   onPressed: () {
                     print("Present second page!");
-                    FlutterBoost.singleton.open("second",urlParams:<dynamic,dynamic>{"present":true}).then((Map value) {
+                    FlutterBoost.singleton.open("second",urlParams:<String,dynamic>{"present":true}).then((Map value) {
                       print(
                           "call me when page is finished. did recieve second route result $value");
                     });
@@ -90,7 +90,7 @@ class SecondRouteWidget extends StatelessWidget {
             BoostContainerSettings settings =
                 BoostContainer.of(context).settings;
             FlutterBoost.singleton.close(settings.uniqueId,
-                result: <dynamic,dynamic>{"result": "data from second"});
+                result: <String,dynamic>{"result": "data from second"});
           },
           child: Text('Go back with result!'),
         ),
@@ -206,7 +206,7 @@ class _FlutterRouteWidgetState extends State<FlutterRouteWidget> {
                   ///后面的参数会在native的IPlatform.startActivity方法回调中拼接到url的query部分。
                   ///例如：sample://nativePage?aaa=bbb
                   onTap: () => FlutterBoost.singleton
-                      .open("sample://nativePage", urlParams: <dynamic,dynamic>{
+                      .open("sample://nativePage", urlParams: <String,dynamic>{
                     "query": {"aaa": "bbb"}
                   }),
                 ),
@@ -223,7 +223,7 @@ class _FlutterRouteWidgetState extends State<FlutterRouteWidget> {
                   ///后面的参数会在native的IPlatform.startActivity方法回调中拼接到url的query部分。
                   ///例如：sample://nativePage?aaa=bbb
                   onTap: () => FlutterBoost.singleton
-                      .open("first", urlParams: <dynamic,dynamic>{
+                      .open("first", urlParams: <String,dynamic>{
                     "query": {"aaa": "bbb"}
                   }),
                 ),
@@ -240,7 +240,7 @@ class _FlutterRouteWidgetState extends State<FlutterRouteWidget> {
                   ///后面的参数会在native的IPlatform.startActivity方法回调中拼接到url的query部分。
                   ///例如：sample://nativePage?aaa=bbb
                   onTap: () => FlutterBoost.singleton
-                      .open("second", urlParams:<dynamic,dynamic> {
+                      .open("second", urlParams:<String,dynamic> {
                     "query": {"aaa": "bbb"}
                   }),
                 ),
@@ -257,7 +257,7 @@ class _FlutterRouteWidgetState extends State<FlutterRouteWidget> {
                   ///后面的参数会在native的IPlatform.startActivity方法回调中拼接到url的query部分。
                   ///例如：sample://nativePage?aaa=bbb
                   onTap: () => FlutterBoost.singleton
-                      .open("tab", urlParams:<dynamic,dynamic> {
+                      .open("tab", urlParams:<String,dynamic> {
                     "query": {"aaa": "bbb"}
                   }),
                 ),
@@ -274,7 +274,7 @@ class _FlutterRouteWidgetState extends State<FlutterRouteWidget> {
                   ///后面的参数会在native的IPlatform.startActivity方法回调中拼接到url的query部分。
                   ///例如：sample://nativePage?aaa=bbb
                   onTap: () => FlutterBoost.singleton
-                      .open("sample://flutterPage", urlParams:<dynamic,dynamic> {
+                      .open("sample://flutterPage", urlParams:<String,dynamic> {
                     "query": {"aaa": "bbb"}
                   }),
                 ),

lib/flutter_boost.dart

@@ -121,8 +121,8 @@ class FlutterBoost {
   }
 
   Future<Map<dynamic, dynamic>> open(String url,
-      {Map<dynamic, dynamic> urlParams, Map<dynamic, dynamic> exts}) {
-    Map<dynamic, dynamic> properties = new Map<dynamic, dynamic>();
+      {Map<String, dynamic> urlParams, Map<String, dynamic> exts}) {
+    Map<dynamic, dynamic> properties = new Map<String, dynamic>();
     properties["url"] = url;
     properties["urlParams"] = urlParams;
     properties["exts"] = exts;
@@ -130,14 +130,14 @@ class FlutterBoost {
   }
 
   Future<bool> close(String id,
-      {Map<dynamic, dynamic> result, Map<dynamic, dynamic> exts}) {
+      {Map<String, dynamic> result, Map<String, dynamic> exts}) {
     assert(id != null);
 
     BoostContainerSettings settings = containerManager?.onstageSettings;
-    Map<dynamic, dynamic> properties = new Map<dynamic, dynamic>();
+    Map<dynamic, dynamic> properties = new Map<String, dynamic>();
 
     if (exts == null) {
-      exts = Map<dynamic, dynamic>();
+      exts = Map<String, dynamic>();
     }
 
     exts["params"] = settings.params;