Fix zoom to selection box when using jQuery 1.9+.

Fixes #1250.

examples/selection/index.html

@@ -12,6 +12,15 @@
 
 	$(function() {
 
+		// Shim allowing us to get the state of the check-box on jQuery versions
+		// prior to 1.6, when prop was added.  The reason we don't just use attr
+		// is because it doesn't work in jQuery versions 1.9.x and later.
+
+		// TODO: Remove this once Flot's minimum supported jQuery reaches 1.6.
+		if (typeof $.fn.prop != 'function') {
+		    $.fn.prop = $.fn.attr;
+		}
+
 		var data = [{
 			label: "United States",
 			data: [[1990, 18.9], [1991, 18.7], [1992, 18.4], [1993, 19.3], [1994, 19.5], [1995, 19.3], [1996, 19.4], [1997, 20.2], [1998, 19.8], [1999, 19.9], [2000, 20.4], [2001, 20.1], [2002, 20.0], [2003, 19.8], [2004, 20.4]]
@@ -64,7 +73,7 @@
 
 			$("#selection").text(ranges.xaxis.from.toFixed(1) + " to " + ranges.xaxis.to.toFixed(1));
 
-			var zoom = $("#zoom").attr("checked");
+			var zoom = $("#zoom").prop("checked");
 
 			if (zoom) {
 				$.each(plot.getXAxes(), function(_, axis) {