Check for the Write properties when calling writeValue on characteris…

…tic (#248)

index.bs

@@ -3038,6 +3038,11 @@ spec: permissions
         <a>a new promise</a> <var>promise</var>
         and run the following steps in parallel.
         <ol>
+          <li>
+            If none of the <code>Write</code>, <code>Write Without Response</code> or <code>Authenticated Signed Writes</code> bits are set
+            in <var>characteristic</var>'s <a lt="Characteristic Properties">properties</a>,
+            <a>reject</a> <var>promise</var> with a {{NotSupportedError}} and abort these steps.
+          </li>
           <li>
             Use any combination of the sub-procedures in
             the <a>Characteristic Value Write</a> procedure

index.html

@@ -3277,6 +3277,7 @@ <h3 class="heading settled dfn-paneled idl-code" data-dfn-type="interface" data-
       <li>
         Return a <code>this.service.device.gatt</code>-<a data-link-type="dfn" href="#connection-checking-wrapper" id="ref-for-connection-checking-wrapper-3">connection-checking wrapper</a> around <a data-link-type="dfn" href="https://www.w3.org/2001/tag/doc/promises-guide/#a-new-promise">a new promise</a> <var>promise</var> and run the following steps in parallel. 
        <ol>
+        <li> If none of the <code>Write</code>, <code>Write Without Response</code> or <code>Authenticated Signed Writes</code> bits are set in <var>characteristic</var>’s <a data-link-type="dfn" href="#characteristic-properties" id="ref-for-characteristic-properties-2">properties</a>, <a data-link-type="dfn" href="https://www.w3.org/2001/tag/doc/promises-guide/#reject-promise">reject</a> <var>promise</var> with a <code class="idl"><a data-link-type="idl" href="https://heycam.github.io/webidl/#notsupportederror">NotSupportedError</a></code> and abort these steps.
         <li> Use any combination of the sub-procedures in
             the <a data-link-type="dfn" href="#characteristic-value-write" id="ref-for-characteristic-value-write-1">Characteristic Value Write</a> procedure
             to write <var>bytes</var> to <var>characteristic</var>.