Remove usage of thix.ctx in initDimensions. (#3441)

* remove this.ctx at text startup.
* fix textbox

src/shapes/textbox.class.js

@@ -57,6 +57,12 @@
      */
     lockScalingFlip: true,
 
+    /**
+     * Override standard Object class values
+     * Textbox needs this on false
+     */
+    noScaleCache: false,
+
     /**
      * Constructor. Some scaling related property values are forced. Visibility
      * of controls is also fixed; only the rotation and width controls are
@@ -96,7 +102,7 @@
       this.dynamicMinWidth = 0;
 
       // wrap lines
-      this._textLines = this._splitTextIntoLines();
+      this._textLines = this._splitTextIntoLines(ctx);
       // if after wrapping, the width is smaller than dynamicMinWidth, change the width and re-wrap
       if (this.dynamicMinWidth > this.width) {
         this._set('width', this.dynamicMinWidth);
@@ -320,14 +326,14 @@
      * @returns {Array} Array of lines in the Textbox.
      * @override
      */
-    _splitTextIntoLines: function() {
+    _splitTextIntoLines: function(ctx) {
       var originalAlign = this.textAlign;
-      this.ctx.save();
-      this._setTextStyles(this.ctx);
+      ctx.save();
+      this._setTextStyles(ctx);
       this.textAlign = 'left';
-      var lines = this._wrapText(this.ctx, this.text);
+      var lines = this._wrapText(ctx, this.text);
       this.textAlign = originalAlign;
-      this.ctx.restore();
+      ctx.restore();
       this._textLines = lines;
       this._styleMap = this._generateStyleMap();
       return lines;