Add range toJSON and fromDict

tracing/tracing/base/range.html

Index: tracing/tracing/base/range.html
diff --git a/tracing/tracing/base/range.html b/tracing/tracing/base/range.html
index b3722146ea7eb2990b5980a4d5b37614ce140e07..767c8671fa386e76f8e8463487497155c5fc4e74 100644
--- a/tracing/tracing/base/range.html
+++ b/tracing/tracing/base/range.html
@@ -132,6 +132,29 @@ tr.exportTo('tr.b', function() {
         return new Range();
 
       return Range.fromExplicitRange(min, max);
+    },
+
+    toJSON: function() {
+      if (this.isEmpty_)
+        return {isEmpty: true};
+      return {
+        isEmpty: false,
+        max: this.max,
+        min: this.min
+      };
+    }
+  };
+
+  Range.fromDict = function(d) {
+    if (d.isEmpty === true) {
+      return new Range();
+    } else if (d.isEmpty === false) {
+      var range = new Range();
+      range.min = d.min;
+      range.max = d.max;
+      return range;
+    } else {
+      throw new Error('Not a range');
     }
   };