fix default axis anchors

we were sorting too late, so if 'y2' was referenced before 'y' in gd.data,
it would become the default anchor for x axes.

Author: alexcjohnson

src/plots/plots.js

@@ -701,11 +701,6 @@ plots.linkSubplots = function(newFullData, newFullLayout, oldFullData, oldFullLa
 
     var i, j, id, ax;
 
-    // sort subplot lists
-    for(var subplotType in newSubplotList) {
-        newSubplotList[subplotType].sort(Lib.subplotSort);
-    }
-
     for(i = 0; i < ids.length; i++) {
         id = ids[i];
         var oldSubplot = oldSubplots[id];
@@ -1390,6 +1385,11 @@ plots.supplyLayoutModuleDefaults = function(layoutIn, layoutOut, fullData, trans
         Cartesian.finalizeSubplots(layoutIn, layoutOut);
     }
 
+    // sort subplot lists
+    for(var subplotType in layoutOut._subplots) {
+        layoutOut._subplots[subplotType].sort(Lib.subplotSort);
+    }
+
     // base plot module layout defaults
     for(i = 0; i < basePlotModules.length; i++) {
         _module = basePlotModules[i];

test/image/mocks/range_slider_axes_stacked.json

@@ -4,7 +4,7 @@
     {"fill": "tozeroy", "y": [30, 20, 10]}
   ],
   "layout": {
-    "xaxis": {"rangeslider": {}, "title": "x", "anchor": "y"},
+    "xaxis": {"rangeslider": {}, "title": "x"},
     "yaxis": {"title": "y", "domain": [0, 0.25]},
     "yaxis2": {"title": "y2", "domain": [ 0.3, 1]}
   }