update elements and fix some bugs

lib/src/iron-range-behavior/iron-range-behavior.html

Index: lib/src/iron-range-behavior/iron-range-behavior.html
diff --git a/lib/src/iron-range-behavior/iron-range-behavior.html b/lib/src/iron-range-behavior/iron-range-behavior.html
index 4306e6924e51134aca979cc5ecd7bdd04e956b1e..28469e9eaeb15a06e3e363d8c27e415b14de9648 100644
--- a/lib/src/iron-range-behavior/iron-range-behavior.html
+++ b/lib/src/iron-range-behavior/iron-range-behavior.html
@@ -12,11 +12,11 @@ subject to an additional IP rights grant found at http://polymer.github.io/PATEN
 
 <script>
 
- /** 
+ /**
  * `iron-range-behavior` provides the behavior for something with a minimum to maximum range.
  *
  * @demo demo/index.html
- * @polymerBehavior 
+ * @polymerBehavior
  */
  Polymer.IronRangeBehavior = {
 
@@ -85,13 +85,16 @@ subject to an additional IP rights grant found at http://polymer.github.io/PATEN
   _calcStep: function(value) {
    /**
     * if we calculate the step using
-    * `Math.round(value / step) * step` we may hit a precision point issue 
+    * `Math.round(value / step) * step` we may hit a precision point issue
     * eg. 0.1 * 0.2 =  0.020000000000000004
     * http://docs.oracle.com/cd/E19957-01/806-3568/ncg_goldberg.html
     *
     * as a work around we can divide by the reciprocal of `step`
     */
-    return this.step ? (Math.round(value / this.step) / (1 / this.step)) : value;
+    // polymer/issues/2493
+    value = parseFloat(value);
+    return this.step ? (Math.round((value + this.min) / this.step) -
+        (this.min / this.step)) / (1 / this.step) : value;
   },
 
   _validateValue: function() {