Remove "in-daylight-saving-time" flag

This flag is problematic because when a time zone is "in DST" is not well
defined. Most time zones in the world don't use DST at all. Of the ones
that do, most go to DST during the summer for half the year, but not all.

For example, the function in Moment.js that provides this functionality
comes with a giant caveat:
https://momentjs.com/docs/#/query/is-daylight-saving-time/

Author: ptomato

imports.md

@@ -190,22 +190,14 @@ should be the string <code>UTC</code>.</p>
 <p>In time zones that do not have an applicable name, a formatted
 representation of the UTC offset may be returned, such as <code>-04:00</code>.</p>
 </li>
-<li>
-<p><a name="timezone_display.in_daylight_saving_time"></a><code>in-daylight-saving-time</code>: <code>bool</code></p>
-<p>Whether daylight saving time is active.
-<p>In implementations that do not expose an actual time zone, this
-should return false.</p>
-</li>
 </ul>
 <hr />
 <h3>Functions</h3>
 <h4><a name="display"></a><code>display: func</code></h4>
 <p>Return information needed to display the given <a href="#instant"><code>instant</code></a>. This includes
-the UTC offset, the time zone name, and a flag indicating whether
-daylight saving time is active.</p>
+the UTC offset and the time zone name.</p>
 <p>If the timezone cannot be determined for the given <a href="#instant"><code>instant</code></a>, return a
-<a href="#timezone_display"><code>timezone-display</code></a> for <code>UTC</code> with a <a href="#utc_offset"><code>utc-offset</code></a> of 0 and no daylight
-saving time.</p>
+<a href="#timezone_display"><code>timezone-display</code></a> for <code>UTC</code> with a <a href="#utc_offset"><code>utc-offset</code></a> of 0.</p>
 <h5>Params</h5>
 <ul>
 <li><a name="display.when"></a><code>when</code>: <a href="#instant"><a href="#instant"><code>instant</code></a></a></li>

wit/timezone.wit

@@ -6,12 +6,10 @@ interface timezone {
     use system-clock.{instant};
 
     /// Return information needed to display the given `instant`. This includes
-    /// the UTC offset, the time zone name, and a flag indicating whether
-    /// daylight saving time is active.
+    /// the UTC offset and the time zone name.
     ///
     /// If the timezone cannot be determined for the given `instant`, return a
-    /// `timezone-display` for `UTC` with a `utc-offset` of 0 and no daylight
-    /// saving time.
+    /// `timezone-display` for `UTC` with a `utc-offset` of 0.
     @unstable(feature = clocks-timezone)
     display: func(when: instant) -> timezone-display;
 
@@ -45,11 +43,5 @@ interface timezone {
         /// In time zones that do not have an applicable name, a formatted
         /// representation of the UTC offset may be returned, such as `-04:00`.
         name: string,
-
-        /// Whether daylight saving time is active.
-        ///
-        /// In implementations that do not expose an actual time zone, this
-        /// should return false.
-        in-daylight-saving-time: bool,
     }
 }