Bug 518623 - [lsp] Content assist assumes ServerCapabilities.Completi…

…onOptions.triggerCharacters is defined

The LSP defines the triggerCharacters property on a
ServerCapabilities' CompletionOptions as optional. So, Orion should
not try to read and consume that value without first checking that it
exists as a language server is not obligated to define a value for
that property.

bundles/org.eclipse.orion.client.editor/web/orion/editor/contentAssist.js

@@ -747,9 +747,12 @@ define("orion/editor/contentAssist", [ //$NON-NLS-0$
 
 							// build up the regex for triggerCharacters
 							var triggers = "[";
-							completionOptions.triggerCharacters.forEach(function(character) {
-							triggers += character;
-							});
+							// don't assume that the language server supports trigger characters
+							if (completionOptions.triggerCharacters) {
+								completionOptions.triggerCharacters.forEach(function(character) {
+									triggers += character;
+								});
+							}
 							triggers += "]";
 							info.charTriggers = new RegExp(triggers);
 						}