[css-transitions-2] Replace references to sampling with animation frames

Author: birtles

css-transitions-2/Overview.bs

@@ -224,11 +224,11 @@ accounts for the full complexity of the Web Animations model.
 
 To avoid firing redundant events, the set of events to dispatch is based
 on comparing the <a lt="transition phase">phase</a> of the transition in the
-previous <a lt="sampling">sample</a> (animation frame) to its current state.
+previous [=animation frame=] to its current state.
 
 The <dfn>transition phase</dfn> of a transition is initially &lsquo;idle&rsquo;
-and is updated on each sample according to the first matching condition from
-below:
+and is updated on each [=animation frame=] according to
+the first matching condition from below:
 
 <dl class=switch>
    <dt>If the transition has no [=associated effect=],
@@ -267,9 +267,10 @@ duration</a>, <a>current iteration</a>, <a>iteration start</a>, and
 [=iteration duration=] of a transition should be understood to refer
 to the corresponding properties of the transition's [=associated effect=].
 
-Each time an animation is <a lt="sampling">sampled</a>, the events to
-dispatch are determined by comparing the <a>transition phase</a> before and
-after the sample as follows:
+Each time a new [=animation frame=] is established,
+the events to dispatch are determined by comparing
+the <a>transition phase</a> in the previous and current [=animation frame=]
+as follows:
 
 <table class="event-state-transitions">
   <thead>