hgweb: properly iterate over arrays and objects in mercurial.js

In JavaScript, using for-in loops to access every property of an object can
have unexpected results when inheritance is involved. For example, if some
piece of code adds a property (it may be a method too) to Object.prototype,
then all for-in loops that iterate over keys of any object (also anything that
inherits Object) will get that property on one of the iterations. To filter out
such unexpected properties for-in loops have to use Object.hasOwnProperty()
method. (This corresponds to "forin" option of jshint).

In the two first cases "data" and "edges" are arrays, to it's simpler to just
switch to using a regular for-with-a-counter loop.

mercurial/templates/static/mercurial.js

@@ -95,7 +95,7 function Graph() {
 		var backgrounds = '';
 		var nodedata = '';
 
-		for (var i in data) {
+		for (var i = 0; i < data.length; i++) {
 
 			var parity = i % 2;
 			this.cell[1] += this.bg_height;
@@ -107,7 +107,7 function Graph() {
 			var fold = false;
 
 			var prevWidth = this.ctx.lineWidth;
-			for (var j in edges) {
+			for (var j = 0; j < edges.length; j++) {
 
 				line = edges[j];
 				start = line[0];
@@ -227,6 +227,7 function process_dates(parentSelector){
 		}
 
 		for (var unit in scales){
+			if (!scales.hasOwnProperty(unit)) { continue; }
 			var s = scales[unit];
 			var n = Math.floor(delta / s);
 			if ((n >= 2) || (s === 1)){