[web-animations-1] Update references to timing-function production, to easing-function

Author: birtles

web-animations-1/Overview.bs

@@ -4480,7 +4480,7 @@ dictionary OptionalEffectTiming {
 ::  The <a>timing function</a> used to scale the time to
     produce easing effects.
 
-    The syntax of the string is defined by the <<timing-function>>
+    The syntax of the string is defined by the <<easing-function>>
     production [[!CSS-EASING-1]].
 
 </div>
@@ -4554,7 +4554,7 @@ the following steps:
     a <span class=exceptionname>TypeError</span> and abort this procedure.
 
 1.  If the {{EffectTiming/easing}} member of |input| is <a>present</a>
-    but cannot be parsed using the <<timing-function>> production
+    but cannot be parsed using the <<easing-function>> production
     [[!CSS-EASING-1]], <a>throw</a> a <span class=exceptionname>TypeError</span>
     and abort this procedure.