[css-timing] Drop clamping from steps() timing function

Author: birtles

css-timing/Overview.bs

@@ -234,17 +234,14 @@ The [=output progress value=] is calculated from the [=input progress value=]
 and [=before flag=] as follows:
 
 1.   Calculate the <var>current step</var> as <code>floor([=input progress
-     value=] &times; [=steps=])</code> clamped to the range [0,
-     [=steps=]].
+     value=] &times; [=steps=])</code>.
 
-1.   If the [=step position=] property is <a value for="steps()">start</a> and
-     <var>current step</var> &lt; [=steps=], increment <var>current
-     step</var> by one.
+1.   If the [=step position=] property is <a value for="steps()">start</a>,
+     increment <var>current step</var> by one.
 
-1.   If <em>all</em> of the following conditions are true:
+1.   If <em>both</em> of the following conditions are true:
 
-     *   the [=before flag=] is set,
-     *   <var>current step</var> &gt; 0, <em>and</em>
+     *   the [=before flag=] is set, <em>and</em>
      *   [=input progress value=] &times; [=steps=] mod 1 equals zero
          (that is, if [=input progress value=] &times; [=steps=] is
          integral), then