Fixes #8635 again (fix was lost in rewrite). Also removes unnecessary "manual" garbage collection.

src/support.js

@@ -73,7 +73,7 @@ jQuery.support = (function() {
 		// Make sure that a selected-by-default option has a working selected property.
 		// (WebKit defaults to false instead of true, IE too, if it's in an optgroup)
 		optSelected: opt.selected,
-		
+
 		// Test setAttribute on camelCase class. If it works, we need attrFixes when doing get/setAttribute (ie6/7)
 		getSetAttribute: div.className !== "t",
 
@@ -196,7 +196,7 @@ jQuery.support = (function() {
 		marginDiv.style.marginRight = "0";
 		div.appendChild( marginDiv );
 		support.reliableMarginRight =
-			( parseInt( document.defaultView.getComputedStyle( marginDiv ).marginRight, 10 ) || 0 ) === 0;
+			( parseInt( document.defaultView.getComputedStyle( marginDiv, null ).marginRight, 10 ) || 0 ) === 0;
 	}
 
 	// Remove the body element we added
@@ -224,9 +224,6 @@ jQuery.support = (function() {
 		}
 	}
 
-	// release memory in IE
-	body = div = all = a = tds = undefined;
-
 	return support;
 })();