[acgiow] (2) Make <img src=''> a special case. (credit: bz)

git-svn-id: http://svn.whatwg.org/webapps@2566 340c8d12-0b0e-0410-8428-c7bf67bfef74

index

  <p>The <code title=attr-img-src><a href=#attr-img-src>src</a></code> attribute must be
  present, and must contain a <a href=#valid-url>valid URL</a> referencing a
  non-interactive, optionally animated, image resource that is neither
  paged nor scripted.</p>
  paged nor scripted. If the <i>base URI of the element</i> is the
  same as <a href="#the-document's-address">the document's address</a>, then the <code title=attr-img-src><a href=#attr-img-src>src</a></code> attribute's value must not be the
  empty string.</p>

  <p class=note>Images can thus be static bitmaps (e.g. PNGs, GIFs,
  JPEGs), single-page vector documents (single-page PDFs, XML files
  user agent must <a href=#fetch>fetch</a> the resource specifed by the
  <code title=attr-img-src><a href=#attr-img-src>src</a></code> attribute's value, unless the
  user agent cannot support images, or its support for images has been
  disabled, or the user agent only fetches elements on demand.</p>
  <!-- Note how this does NOT happen when the base URL changes. -->
  disabled, or the user agent only fetches elements on demand, or the
  element's <code title=attr-img-src><a href=#attr-img-src>src</a></code> attribute has a
  value that is an <i>ignored self-reference</i>.</p> <!-- Note how
  this does NOT happen when the base URL changes. -->

  <p>The <code title=attr-img-src><a href=#attr-img-src>src</a></code> attribute's value is an
  <i>ignored self-reference</i> if its value is the empty string, and
  the <i>base URI of the element</i> is the same as <a href="#the-document's-address">the
  document's address</a>.</p>

  <p>Fetching the image must <a href=#delay-the-load-event>delay the <code title=event-load>load</code> event</a>.</p>

  the image is being <a href=#fetch title=fetch>fetched</a> must update
  the presentation of the image appropriately.</p>

  <p>If the image was not fetched (e.g. because the UA's image support
  is disabled, or because the <code title=attr-img-src><a href=#attr-img-src>src</a></code>
  attribute's value is an <i>ignored self-reference</i>), or if the
  conditions in the previous paragraph are not met, then the image is
  <em>not</em> <i>available</i>.</p>

  <p>Whether the image is fetched successfully or not (e.g. whether
  the response code was a 2xx code <a href=#concept-http-equivalent-codes title=concept-http-equivalent-codes>or equivalent</a>) must be
  ignored when determining the image's type and whether it is a valid
    the content, redundant with some other information in the
    document.</p>

    <p>If the image is <i>available</i> and the user agent is configured to
    display that image, then the element represents the image
    specified by the <code title=attr-img-src><a href=#attr-img-src>src</a></code>
    <p>If the image is <i>available</i> and the user agent is
    configured to display that image, then the element represents the
    image specified by the <code title=attr-img-src><a href=#attr-img-src>src</a></code>
    attribute.</p>

    <p>Otherwise, the element represents nothing, and may be omitted

source

  <p>The <code title="attr-img-src">src</code> attribute must be
  present, and must contain a <span>valid URL</span> referencing a
  non-interactive, optionally animated, image resource that is neither
  paged nor scripted.</p>
  paged nor scripted. If the <i>base URI of the element</i> is the
  same as <span>the document's address</span>, then the <code
  title="attr-img-src">src</code> attribute's value must not be the
  empty string.</p>

  <p class="note">Images can thus be static bitmaps (e.g. PNGs, GIFs,
  JPEGs), single-page vector documents (single-page PDFs, XML files
  user agent must <span>fetch</span> the resource specifed by the
  <code title="attr-img-src">src</code> attribute's value, unless the
  user agent cannot support images, or its support for images has been
  disabled, or the user agent only fetches elements on demand.</p>
  <!-- Note how this does NOT happen when the base URL changes. -->
  disabled, or the user agent only fetches elements on demand, or the
  element's <code title="attr-img-src">src</code> attribute has a
  value that is an <i>ignored self-reference</i>.</p> <!-- Note how
  this does NOT happen when the base URL changes. -->

  <p>The <code title="attr-img-src">src</code> attribute's value is an
  <i>ignored self-reference</i> if its value is the empty string, and
  the <i>base URI of the element</i> is the same as <span>the
  document's address</span>.</p>

  <p>Fetching the image must <span>delay the <code
  title="event-load">load</code> event</span>.</p>
  the image is being <span title="fetch">fetched</span> must update
  the presentation of the image appropriately.</p>

  <p>If the image was not fetched (e.g. because the UA's image support
  is disabled, or because the <code title="attr-img-src">src</code>
  attribute's value is an <i>ignored self-reference</i>), or if the
  conditions in the previous paragraph are not met, then the image is
  <em>not</em> <i>available</i>.</p>

  <p>Whether the image is fetched successfully or not (e.g. whether
  the response code was a 2xx code <span
  title="concept-http-equivalent-codes">or equivalent</span>) must be
    the content, redundant with some other information in the
    document.</p>

    <p>If the image is <i>available</i> and the user agent is configured to
    display that image, then the element represents the image
    specified by the <code title="attr-img-src">src</code>
    <p>If the image is <i>available</i> and the user agent is
    configured to display that image, then the element represents the
    image specified by the <code title="attr-img-src">src</code>
    attribute.</p>

    <p>Otherwise, the element represents nothing, and may be omitted