address issue 5289 - use if block instead of loop

Author: archmoj

src/traces/histogram/cross_trace_defaults.js

@@ -174,10 +174,9 @@ module.exports = function crossTraceDefaults(fullData, fullLayout) {
         }
 
         var binGroupFound = false;
-        for(i = 0; i < traces.length; i++) {
-            traceOut = traces[i];
+        if(traces.length) {
+            traceOut = traces[0];
             binGroupFound = coerce('bingroup');
-            break;
         }
 
         groupName = binGroupFound || groupName;