GLTFExporter: Include forceIndices on examples

examples/misc_exporter_gltf.html

@@ -33,6 +33,7 @@
 			<label><input id="option_visible" name="visible" type="checkbox" checked="checked"/>Only Visible</label>
 			<label><input id="option_drawrange" name="visible" type="checkbox" checked="checked"/>Truncate drawRange</label>
 			<label><input id="option_binary" name="visible" type="checkbox">Binary (<code>.glb</code>)</label>
+			<label><input id="option_forceindices" name="visible" type="checkbox">Force indices</label>
 		</div>
 
 		<script src="../build/three.js"></script>
@@ -50,7 +51,8 @@
 					trs: document.getElementById('option_trs').checked,
 					onlyVisible: document.getElementById('option_visible').checked,
 					truncateDrawRange: document.getElementById('option_drawrange').checked,
-					binary: document.getElementById('option_binary').checked
+					binary: document.getElementById('option_binary').checked,
+					forceIndices: document.getElementById('option_forceindices').checked
 				};
 				gltfExporter.parse( input, function( result ) {