refactor: 优化 canvas 实例 data 写法

pages/component/canvas/canvas.uvue

@@ -55,13 +55,14 @@
     context.scale(dpr, dpr);
   }
 
+
+  export default {
+    data() {
       const API_PATH = ["arc", "arcTo", "bezierCurveTo", "quadraticCurve", "moveTo", "lineTo", "rect", "clip", "pattern"]
       const API_DRAW = ["stroke", "strokeRect", "strokeText", "fill", "fillRect", "fillText", "drawImage", "drawImageLocal", "clearRect"]
       const API_STATE = ["beginPath", "closePath", "reset", "transform", "rotate", "resetTransform", "save", "restore", "scale", "translate"]
       const API_PROPERTIES = ["setLineCap", "setLineJoin", "setLineWidth", "setMiterLimit", "setFillStyle", "setStrokeStyle", "setGlobalAlpha", "setFontSize", "lineDash", "linearGradient", "radialGradient", "textAlign"]
 
-  export default {
-    data() {
       return {
         title: 'Context2D',
         canvas: null as UniCanvasElement | null,