Bug 774169, patch 1: Make the property_database.js-based tests call getComputedStyle() for all properties that are expected to have longhand behavior. r=bzbarsky

This currently only affects the testing of overflow, but it will also
affect -moz-transform (and any other aliases implemented the same way)
after the later patches in this bug.

This special-cases text-decoration because text-decoration: inherit causes
the color to inherit in a way that we can't serialize the result (since
it's no longer "foreground").  (This isn't great; we might want to
consider fixing it somehow.)

layout/style/test/property_database.js

@@ -3873,7 +3873,9 @@ function logical_box_prop_get_computed(cs, property)
 function get_computed_value(cs, property)
 {
 	var info = gCSSProperties[property];
-	if ("subproperties" in info) {
+	if (info.type == CSS_TYPE_TRUE_SHORTHAND ||
+	    (info.type == CSS_TYPE_SHORTHAND_AND_LONGHAND &&
+	     property == "text-decoration")) {
 		var results = [];
 		for (var idx in info.subproperties) {
 			var subprop = info.subproperties[idx];