Fix layout calculation for multiline legend elements.

Previously if the user specified a legend element that spanned multiple
lines (included <br>), Plotly would calculate the legend item's width as
if it were:
    multi
         line
	     legend

instead of:
    multi
    line
    legend

This ended up being caused by a stale bbox stored in Plotly's cache.
The solution for now is to force bbox recalculation for this particular
bbox in the legend component. I'm not sure if this is the long term
solution though.

Author: John Soklaski

dist/plotly-geo-assets.js

@@ -483,12 +483,14 @@ drawing.makeTester = function(gd) {
 // always returns a copy of the bbox, so the caller can modify it safely
 var savedBBoxes = [],
     maxSavedBBoxes = 10000;
-drawing.bBox = function(node) {
+drawing.bBox = function(node, forceReCalc) {
     // cache elements we've already measured so we don't have to
     // remeasure the same thing many times
-    var saveNum = node.attributes['data-bb'];
-    if(saveNum && saveNum.value) {
-        return Plotly.Lib.extendFlat({}, savedBBoxes[saveNum.value]);
+    if(!forceReCalc) {
+        var saveNum = node.attributes['data-bb'];
+        if(saveNum && saveNum.value) {
+            return Plotly.Lib.extendFlat({}, savedBBoxes[saveNum.value]);
+        }
     }
 
     var test3 = d3.select('#js-plotly-tester'),

dist/plotly-with-meta.js

@@ -583,7 +583,7 @@ legend.repositionLegend = function(td, traces){
             tspans = g.selectAll('.legendtext>tspan'),
             tHeight = opts.font.size * 1.3,
             tLines = tspans[0].length||1,
-            tWidth = text.node() && Plotly.Drawing.bBox(text.node()).width,
+            tWidth = text.node() && Plotly.Drawing.bBox(text.node(), true).width,
             mathjaxGroup = g.select('g[class*=math-group]'),
             textY,
             tHeightFull;