[css-properties-values-api] correct computation for transform functions.

Author: shans

css-properties-values-api/Overview.bs

@@ -413,14 +413,17 @@ For <length-percentage> values, the computed value is one of the following:
 	length expressed in pixels, and a percentage value.
 
 For <custom-ident>, ident, <color>, <image>, <url>, <integer>,
-<angle>, <time>, <resolution>, <transform-function> or "*" values, the
-computed value is identical to the specified value.
+<angle>, <time>, <resolution> or "*" values, the
+computed value is as specified.
 
 For <number> and <percentage> values which are not calc expressions, the
-computed value is identical to the specified value. Calc expressions that are
+computed value is as specified. Calc expressions that are
 <number> and <percentage> values get reduced during computation to simple
 numbers and percentages respectively.
 
+For <transform-function> values, the computed value is as specified but with
+all lengths resolved to their computed values.
+
 For values specified by a syntax string that include "|" clauses, the computed
 value is given by applying the calculation rules for the first clause that
 matches to the specified value.