integrate fullLayout inverseTransform and m shorthand

Co-authored-by: Alex Johnson <johnson.alex.c@gmail.com>

Author: archmoj

src/plot_api/plot_api.js

@@ -3715,8 +3715,7 @@ function makePlotFramework(gd) {
     var gd3 = d3.select(gd);
     var fullLayout = gd._fullLayout;
     if(fullLayout._inverseTransform === undefined) {
-        fullLayout._inverseTransform = Lib.inverseTransformMatrix(Lib.getFullTransformMatrix(gd));
-        var m = fullLayout._inverseTransform;
+        var m = fullLayout._inverseTransform = Lib.inverseTransformMatrix(Lib.getFullTransformMatrix(gd));
         fullLayout._inverseScaleX = Math.sqrt(m[0][0] * m[0][0] + m[0][1] * m[0][1] + m[0][2] * m[0][2]);
         fullLayout._inverseScaleY = Math.sqrt(m[1][0] * m[1][0] + m[1][1] * m[1][1] + m[1][2] * m[1][2]);
     }