Fixes histogram plot disappears when time range is too small (issue e…

…lastic#733)

This fixes rounding behaviour in interval_to_ms. The interval_to_ms
function will round any fractional component of an interval to 0 because
it tries to parse it as an integer.

I've fixed it by trying by parsing as a float but then trying to preserve
the existing behaviour of returning integer results in the callers.

closes elasticsearch/kibana/elastic#733

src/app/components/kbn.js

@@ -228,19 +228,19 @@ function($, _, moment) {
       return {
         sec: kbn.intervals_in_seconds[matches[2]],
         type: matches[2],
-        count: parseInt(matches[1], 10)
+        count: parseFloat(matches[1])
       };
     }
   };
 
   kbn.interval_to_ms = function(string) {
     var info = kbn.describe_interval(string);
-    return info.sec * 1000 * info.count;
+    return Math.ceil(info.sec * 1000 * info.count);
   };
 
   kbn.interval_to_seconds = function (string) {
     var info = kbn.describe_interval(string);
-    return info.sec * info.count;
+    return Math.ceil(info.sec * info.count);
   };
 
   // This should go away, moment.js can do this

src/app/panels/histogram/interval.js

@@ -13,7 +13,7 @@ function (kbn) {
 
     var info = kbn.describe_interval(interval_string);
     this.type = info.type;
-    this.ms = info.sec * 1000 * info.count;
+    this.ms = Math.ceil(info.sec * 1000 * info.count);
 
     // does the length of the interval change based on the current time?
     if (this.type === 'y' || this.type === 'M') {

src/app/panels/sparklines/interval.js

@@ -13,7 +13,7 @@ function (kbn) {
 
     var info = kbn.describe_interval(interval_string);
     this.type = info.type;
-    this.ms = info.sec * 1000 * info.count;
+    this.ms = Math.ceil(info.sec * 1000 * info.count);
 
     // does the length of the interval change based on the current time?
     if (this.type === 'y' || this.type === 'M') {