Fix regl check

Author: jonmmease

src/plot_api/plot_api.js

@@ -221,19 +221,20 @@ function _doPlot(gd, data, layout, config) {
                 });
         }
 
+        var plotGlPixelRatio = gd._context.plotGlPixelRatio
         if(fullLayout._glcanvas) {
             fullLayout._glcanvas
-                .attr('width', fullLayout.width * gd._context.plotGlPixelRatio)
-                .attr('height', fullLayout.height * gd._context.plotGlPixelRatio)
+                .attr('width', fullLayout.width * plotGlPixelRatio)
+                .attr('height', fullLayout.height * plotGlPixelRatio)
                 .style('width', fullLayout.width + 'px')
                 .style('height', fullLayout.height + 'px');
 
             var regl = fullLayout._glcanvas.data()[0].regl;
             if(regl) {
                 // Unfortunately, this can happen when relayouting to large
                 // width/height on some browsers.
-                if(Math.floor(fullLayout.width) !== regl._gl.drawingBufferWidth ||
-                    Math.floor(fullLayout.height) !== regl._gl.drawingBufferHeight
+                if(Math.floor(fullLayout.width * plotGlPixelRatio) !== regl._gl.drawingBufferWidth ||
+                    Math.floor(fullLayout.height * plotGlPixelRatio) !== regl._gl.drawingBufferHeight
                  ) {
                     var msg = 'WebGL context buffer and canvas dimensions do not match due to browser/WebGL bug.';
                     if(drawFrameworkCalls) {