Refactor the caching for tester DOM into the makeTester function of drawing module

Author: hy9be

src/components/drawing/index.js

@@ -496,6 +496,9 @@ drawing.makeTester = function(gd) {
 
     gd._tester = tester;
     gd._testref = testref;
+
+    drawing.tester = tester.node();
+    drawing.refRect = testref.node().getBoundingClientRect();
 };
 
 // use our offscreen tester to get a clientRect for an element,
@@ -513,11 +516,6 @@ drawing.bBox = function(node) {
         return Lib.extendFlat({}, savedBBoxes[saveNum.value]);
     }
 
-    if(!drawing.test3) {
-        drawing.test3 = d3.select('#js-plotly-tester');
-        drawing.tester = drawing.test3.node();
-    }
-
     // copy the node to test into the tester
     var testNode = node.cloneNode(true);
     drawing.tester.appendChild(testNode);
@@ -529,10 +527,6 @@ drawing.bBox = function(node) {
     });
 
     var testRect = testNode.getBoundingClientRect();
-    if(!drawing.refRect) {
-        drawing.refRect = drawing.test3.select('.js-reference-point')
-            .node().getBoundingClientRect();
-    }
 
     drawing.tester.removeChild(testNode);