Removed paragraph talking about UAs skipping over image() arguments based on extension.

Reworked paragraph describing the final argument of image().

Author: tabatkins

css3-images/Overview.html

@@ -415,12 +415,12 @@ <h3 id=image-notation><span class=secno>4.2. </span>Image Fallbacks: the
      pixel rounding" is the right terminology here... basically we want to
      avoid blurry images.</span></p>
 
-    <p>The optional color at the end of the list is the <dfn
-     id=fallback-color>fallback color</dfn>. It is used if, and only if, none
-     of the images can be loaded and displayed (e.g. because they are in
-     unsupported formats, or cannot be found, or are corrupted in some way,
-     or because image loading is disabled in the UA). It is treated as a
-     single-color image with no intrinsic dimensions.
+    <p>The final argument may be a color or generated image, to serve as an
+     ultimate fallback if none of the preceeding <a
+     href="#ltimage-decl"><b>&lt;image-decl></b></a>s can be used. If it is a
+     color, the <a href="#ltimage-list"><b>&lt;image-list></b></a> must
+     represent a single-color image of that color with no <a
+     href="#intrinsic-dimensions"><b>intrinsic dimensions</b></a>.</p>
 
     <div class=example>
      <p>For example, the rule below would tell the UA to load &lsquo;<code
@@ -441,17 +441,6 @@ <h3 id=image-notation><span class=secno>4.2. </span>Image Fallbacks: the
       As with any image, this fallback will be painted over the &lsquo;<code
       class=property>background-color</code>&rsquo; (if any).
     </div>
-
-    <p>If the URL for the image ends in a file extension (a period followed
-     by letters) of four ascii letters ([a-zA-Z]) or less, then the UA
-     <em>may</em> skip trying to load images whose file extension matches an
-     image format it knows it does not support. For example, a UA that knows
-     it supports JPEG and GIF, but expects to encounter many PNG and SVG
-     images may choose to skip over images with filenames ending in
-     &lsquo;<code class=css>.png</code>&rsquo; or &lsquo;<code
-     class=css>.svg</code>&rsquo; without loading them to check their MIME
-     type. However it must not skip over images with filenames ending in
-     extensions it doesn't recognize.
    </div>
 
    <div>

css3-images/Overview.src.html

@@ -204,11 +204,10 @@ <h3 id="image-notation">Image Fallbacks: the ''image()'' notation</h3>
 		"no pixel rounding" is the right terminology here... basically we want to
 		avoid blurry images.</span></p>
 
-		<p>The optional color at the end of the list is the <dfn>fallback color</dfn>.
-		It is used if, and only if, none of the images can be loaded and displayed
-		(e.g. because they are in unsupported formats, or cannot be found, or are
-		corrupted in some way, or because image loading is disabled in the UA). It
-		is treated as a single-color image with no intrinsic dimensions.
+		<p>The final argument may be a color or generated image, to serve as an
+		ultimate fallback if none of the preceeding <b>&lt;image-decl></b>s can be used.  
+		If it is a color, the <b>&lt;image-list></b> must represent a single-color 
+		image of that color with no <b>intrinsic dimensions</b>.</p>
 
 		<div class="example">
 		 <p>For example, the rule below would tell the UA to load ''wavy.svg'' if
@@ -223,15 +222,6 @@ <h3 id="image-notation">Image Fallbacks: the ''image()'' notation</h3>
 			 the background will be painted blue. As with any image, this fallback
 			 will be painted over the 'background-color' (if any).
 		</div>
-
-		<p>If the URL for the image ends in a file extension (a period followed by
-		letters) of four ascii letters ([a-zA-Z]) or less, then the UA <em>may</em>
-		skip trying to load images whose file extension matches an image format it
-		knows it does not support. For example, a UA that knows it supports JPEG and
-		GIF, but expects to encounter many PNG and SVG images may choose to skip over
-		images with filenames ending in '.png' or '.svg' without loading them to
-		check their MIME type. However it must not skip over images with filenames
-		ending in extensions it doesn't recognize.
 	</div>
 
 	<div>