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        <tr>
          <th>Bug ID</th>
          <td><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - Safari 8 and 9 have a Date bug with the &quot;milliseconds&quot; param."
   href="https://bugs.webkit.org/show_bug.cgi?id=150386">150386</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>Safari 8 and 9 have a Date bug with the &quot;milliseconds&quot; param.
          </td>
        </tr>

        <tr>
          <th>Classification</th>
          <td>Unclassified
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>WebKit
          </td>
        </tr>

        <tr>
          <th>Version</th>
          <td>WebKit Nightly Build
          </td>
        </tr>

        <tr>
          <th>Hardware</th>
          <td>Unspecified
          </td>
        </tr>

        <tr>
          <th>URL</th>
          <td>https://github.com/es-shims/es5-shim/issues/329
          </td>
        </tr>

        <tr>
          <th>OS</th>
          <td>Unspecified
          </td>
        </tr>

        <tr>
          <th>Status</th>
          <td>NEW
          </td>
        </tr>

        <tr>
          <th>Severity</th>
          <td>Critical
          </td>
        </tr>

        <tr>
          <th>Priority</th>
          <td>P2
          </td>
        </tr>

        <tr>
          <th>Component</th>
          <td>JavaScriptCore
          </td>
        </tr>

        <tr>
          <th>Assignee</th>
          <td>webkit-unassigned&#64;lists.webkit.org
          </td>
        </tr>

        <tr>
          <th>Reporter</th>
          <td>ljharb&#64;gmail.com
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>darin&#64;apple.com, fpizlo&#64;apple.com, ggaren&#64;apple.com, utatane.tea&#64;gmail.com
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        </tr></table>
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        <div>
        <pre>See <a href="https://github.com/es-shims/es5-shim/issues/329">https://github.com/es-shims/es5-shim/issues/329</a>

`new Date(1970, 0, 1,0, 0, 0, 2147483647);` produces a valid Date object, `new Date(1970, 0, 1,0, 0, 0, 2147483648);` does not. 2147483648 is, of course, `Math.pow(2, 31)`.

So, the issue seems to be that Safari 8 and 9 - alone amongst the browsers, it's worth noting - is treating the millisecond parameter to `Date` as a signed 32-bit integer - when in fact, it should allow all integer values up to `Number.MAX_SAFE_INTEGER`: ie, a 64-bit signed integer, also known as a normal JS number value.

This does not appear to be an issue for the other parameters to the 7-arg form of the Date constructor, but when fixing this, please verify that all JS Number values work as expected when passed in as any of the 7 arguments.</pre>
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