Fix #12324, line-height "normal" isn't always "1". Close gh-898.

src/css.js

@@ -11,8 +11,7 @@ var curCSS, iframe, iframeDoc,
 	cssShow = { position: "absolute", visibility: "hidden", display: "block" },
 	cssNormalTransform = {
 		letterSpacing: 0,
-		fontWeight: 400,
-		lineHeight: 1
+		fontWeight: 400
 	},
 
 	cssExpand = [ "Top", "Right", "Bottom", "Left" ],

test/unit/css.js

@@ -776,11 +776,10 @@ test("css('width') and css('height') should respect box-sizing, see #11004", fun
 });
 
 test("certain css values of 'normal' should be convertable to a number, see #8627", function() {
-	var el = jQuery("<div style='letter-spacing:normal;font-weight:normal;line-height:normal;'>test</div>").appendTo("#qunit-fixture");
+	var el = jQuery("<div style='letter-spacing:normal;font-weight:normal;'>test</div>").appendTo("#qunit-fixture");
 
 	ok( jQuery.isNumeric( parseFloat( el.css("letterSpacing") ) ), "css('letterSpacing') not convertable to number, see #8627" );
 	ok( jQuery.isNumeric( parseFloat( el.css("fontWeight") ) ), "css('fontWeight') not convertable to number, see #8627" );
-	ok( jQuery.isNumeric( parseFloat( el.css("lineHeight") ) ), "css('lineHeight') not convertable to number, see #8627" );
 });
 
 test( "cssHooks - expand", function() {