fix #2168 - fill in 'id' in bar calcdata

... so that ErrorBars.plot know what do it with it

Author: etpinard

src/traces/bar/calc.js

@@ -48,12 +48,16 @@ module.exports = function calc(gd, trace) {
     }
 
     // create the "calculated data" to plot
-    var serieslen = Math.min(pos.length, size.length),
-        cd = new Array(serieslen);
+    var serieslen = Math.min(pos.length, size.length);
+    var cd = new Array(serieslen);
 
     // set position and size
     for(i = 0; i < serieslen; i++) {
         cd[i] = { p: pos[i], s: size[i] };
+
+        if(trace.ids) {
+            cd[i].id = String(trace.ids[i]);
+        }
     }
 
     // set base

test/image/baselines/error_bar_bar_ids.png

@@ -0,0 +1,20 @@
+{
+  "data": [{  
+    "type":"bar",
+    "x": ["A", "B", "C"],
+    "y": [0, "2.12", "2.32"],
+    "ids": ["A", "B", "C"], 
+    "name": "<b>Sample</b>",
+    "marker": {  
+       "color": "#FFFFCC",
+       "line":{  
+          "color": "rgba(0,0,0,0.4)",
+          "width": 1.5
+       }
+    },
+    "error_y": {  
+       "array": ["1.32", "1.43", "1.58"],
+       "arrayminus": ["1.31", "1.44", "1.57"]
+    }
+  }]
+}