[JSB] Some fixes for cc.DrawNode: (#19889)

- It was using the same _drawColor field for all instances
- drawSegment() was not checking the optional parameters the way web does, which led to different outcomes

cocos/scripting/js-bindings/script/jsb_cocos2d.js

@@ -1779,7 +1779,7 @@ cc._DrawNode.prototype.drawPoly = function (verts, fillColor, borderWidth, borde
     cc._DrawNode.prototype.drawPolygon.call(this, verts, verts.length, fillColor, borderWidth, borderColor);
 }
 cc.DrawNode = cc._DrawNode.extend({
-    _drawColor: cc.color(255, 255, 255, 255),
+    _drawColor: null,
     _lineWidth: 1,
 
     release: function () {},
@@ -1895,7 +1895,9 @@ cc.DrawNode = cc._DrawNode.extend({
         cc._DrawNode.prototype.drawDot.call(this, pos, radius, color);
     },
 
-    drawSegment:function (from, to, lineWidth = this._lineWidth, color = this._drawColor) {
+    drawSegment:function (from, to, lineWidth, color) {
+        lineWidth = lineWidth || this._lineWidth;
+        color = color || this._drawColor;
         cc._DrawNode.prototype.drawSegment.call(this, from, to, lineWidth, color);
     },
 

cocos/scripting/js-bindings/script/jsb_create_apis.js

@@ -774,6 +774,7 @@ cc.ClippingNode.prototype._ctor = function(stencil) {
 
 cc.DrawNode.prototype._ctor = function() {
     cc.DrawNode.prototype.init.call(this);
+    this._drawColor = cc.color(255, 255, 255, 255);
 };
 
 cc.LabelAtlas.prototype._ctor = function(strText, charMapFile, itemWidth, itemHeight, startCharMap) {