Specify the rules for interpolating font-weight.

This is roughly as proposed in
http://lists.w3.org/Archives/Public/www-style/2012Feb/1083.html and
resolved in the 2012 March 7 teleconference (minutes at
http://lists.w3.org/Archives/Public/www-style/2012Mar/0195.html ).

Except I noticed a mistake as described in
http://lists.w3.org/Archives/Public/www-style/2012Mar/0596.html and
fixed it by rounding down instead of rounding to nearest.

Author: dbaron

css3-transitions/Overview.html

@@ -1126,6 +1126,11 @@ <h2 id=animation-of-property-types-><span class=secno>6. </span> Animation
     numbers). The interpolation happens in real number space and is converted
     to an integer using <code>floor()</code>.
 
+   <li> <strong>font weight</strong>: interpolated via discrete steps
+    (multiples of 100). The interpolation happens in real number space and is
+    converted to an integer by rounding down to the nearest smaller or equal
+    multiple of 100.
+
    <li> <strong>number</strong>: interpolated as real (floating point)
     numbers.
 
@@ -1307,7 +1312,7 @@ <h3 id=properties-from-css-><span class=secno>7.1. </span> Properties from
     <tr>
      <td>font-weight
 
-     <td>number <span class=issue>It's not that simple.</span>
+     <td>font weight
 
     <tr>
      <td>height

css3-transitions/Overview.src.html

@@ -1105,6 +1105,12 @@ <h2 id="animation-of-property-types-">
           numbers). The interpolation happens in real number space and is
           converted to an integer using <code>floor()</code>.
         </li>
+        <li>
+          <strong>font weight</strong>: interpolated via discrete steps
+          (multiples of 100). The interpolation happens in real number
+          space and is converted to an integer by rounding down to the
+          nearest smaller or equal multiple of 100.
+        </li>
         <li>
           <strong>number</strong>: interpolated as real (floating point)
           numbers.
@@ -1254,8 +1260,7 @@ <h3>
          <td>font-size</td><td>length, percentage</td>
        </tr>
        <tr>
-         <td>font-weight</td><td>number <span class="issue">It's not
-         that simple.</span></td>
+         <td>font-weight</td><td>font weight</td>
        </tr>
        <tr>
          <td>height</td><td>length, percentage</td>