[css-animations] Fix typo: fro -> from.

Author: dbaron

css-animations/Overview.bs

@@ -1017,7 +1017,7 @@ The <code>findRule</code> method</h4>
 		<dt><dfn argument for="CSSKeyframesRule/findRule()">key</dfn> of type <a interface>DOMString</a>
 		<dd>
 			The key which describes the rule to be deleted. A percentage value between 
-            0% and 100%, or one of the keywords ''fro'' or ''to'' which resolve to 0% and 
+            0% and 100%, or one of the keywords ''from'' or ''to'' which resolve to 0% and 
             100%, respectively.	
     </dl>
 

css-animations/Overview.html

@@ -1038,7 +1038,7 @@ <h4 class="heading settled" data-level=6.3.5 id=interface-csskeyframesrule-findr
 		<dt><dfn class=idl-code data-dfn-for=CSSKeyframesRule/findRule() data-dfn-type=argument data-export="" id=dom-csskeyframesrule-findrule-key>key<a class=self-link href=#dom-csskeyframesrule-findrule-key></a></dfn> of type <a class=idl-code data-link-type=interface title=DOMString>DOMString</a>
 		<dd>
 			The key which describes the rule to be deleted. A percentage value between 
-            0% and 100%, or one of the keywords <span class=css>fro</span> or <span class=css>to</span> which resolve to 0% and 
+            0% and 100%, or one of the keywords <span class=css>from</span> or <span class=css>to</span> which resolve to 0% and 
             100%, respectively.	
     </dl>