CSS: Avoid filling jQuery.cssProps

Fixes jquerygh-3986
Closes jquerygh-4005

Avoids filling jQuery.cssProps by introducing a second internal
prop cache. This allows jQuery Migrate to detect external usage.

Author: dmethvin

src/css.js

@@ -13,12 +13,13 @@ define( [
 	"./css/adjustCSS",
 	"./css/addGetHookIf",
 	"./css/support",
+	"./css/finalPropName",
 
 	"./core/init",
 	"./core/ready",
 	"./selector" // contains
 ], function( jQuery, pnum, access, camelCase, document, rcssNum, rnumnonpx, cssExpand,
-	getStyles, swap, curCSS, adjustCSS, addGetHookIf, support ) {
+	getStyles, swap, curCSS, adjustCSS, addGetHookIf, support, finalPropName ) {
 
 "use strict";
 
@@ -33,40 +34,7 @@ var
 	cssNormalTransform = {
 		letterSpacing: "0",
 		fontWeight: "400"
-	},
-
-	cssPrefixes = [ "Webkit", "Moz", "ms" ],
-	emptyStyle = document.createElement( "div" ).style;
-
-// Return a css property mapped to a potentially vendor prefixed property
-function vendorPropName( name ) {
-
-	// Shortcut for names that are not vendor prefixed
-	if ( name in emptyStyle ) {
-		return name;
-	}
-
-	// Check for vendor prefixed names
-	var capName = name[ 0 ].toUpperCase() + name.slice( 1 ),
-		i = cssPrefixes.length;
-
-	while ( i-- ) {
-		name = cssPrefixes[ i ] + capName;
-		if ( name in emptyStyle ) {
-			return name;
-		}
-	}
-}
-
-// Return a property mapped along what jQuery.cssProps suggests or to
-// a vendor prefixed property.
-function finalPropName( name ) {
-	var ret = jQuery.cssProps[ name ];
-	if ( !ret ) {
-		ret = jQuery.cssProps[ name ] = vendorPropName( name ) || name;
-	}
-	return ret;
-}
+	};
 
 function setPositiveNumber( elem, value, subtract ) {
 

src/css/finalPropName.js

@@ -0,0 +1,39 @@
+define( [ "../var/document" ], function( document ) {
+
+"use strict";
+
+var cssPrefixes = [ "Webkit", "Moz", "ms" ],
+	emptyStyle = document.createElement( "div" ).style,
+	vendorProps = {};
+
+// Return a vendor-prefixed property or undefined
+function vendorPropName( name ) {
+
+	// Check for vendor prefixed names
+	var capName = name[ 0 ].toUpperCase() + name.slice( 1 ),
+		i = cssPrefixes.length;
+
+	while ( i-- ) {
+		name = cssPrefixes[ i ] + capName;
+		if ( name in emptyStyle ) {
+			return name;
+		}
+	}
+}
+
+// Return a potentially-mapped jQuery.cssProps or vendor prefixed property
+function finalPropName( name ) {
+	var final = jQuery.cssProps[ name ] || vendorProps[ name ];
+
+	if ( final ) {
+		return final;
+	}
+	if ( name in emptyStyle ) {
+		return name;
+	}
+	return vendorProps[ name ] = vendorPropName( name ) || name;
+}
+
+return finalPropName;
+
+} );

src/effects/Tween.js

@@ -1,7 +1,9 @@
 define( [
 	"../core",
+	"../css/finalPropName",
+
 	"../css"
-], function( jQuery ) {
+], function( jQuery, finalPropName ) {
 
 "use strict";
 
@@ -84,9 +86,9 @@ Tween.propHooks = {
 			// Use .style if available and use plain properties where available.
 			if ( jQuery.fx.step[ tween.prop ] ) {
 				jQuery.fx.step[ tween.prop ]( tween );
-			} else if ( tween.elem.nodeType === 1 &&
-				( tween.elem.style[ jQuery.cssProps[ tween.prop ] ] != null ||
-					jQuery.cssHooks[ tween.prop ] ) ) {
+			} else if ( tween.elem.nodeType === 1 && (
+					jQuery.cssHooks[ tween.prop ] ||
+					tween.elem.style[ finalPropName( tween.prop ) ] != null ) ) {
 				jQuery.style( tween.elem, tween.prop, tween.now + tween.unit );
 			} else {
 				tween.elem[ tween.prop ] = tween.now;