Textarea Field, Multiline Block (from acbart) (#2663)

* Field Textarea, text_multiline block, generators

generators/dart.js

@@ -183,6 +183,20 @@ Blockly.Dart.quote_ = function(string) {
   return '\'' + string + '\'';
 };
 
+/**
+ * Encode a string as a properly escaped multiline Dart string, complete with
+ * quotes.
+ * @param {string} string Text to encode.
+ * @return {string} Dart string.
+ * @private
+ */
+Blockly.Dart.multiline_quote_ = function(string) {
+  // Can't use goog.string.quote since $ must also be escaped.
+  string = string.replace(/'''/g, '\\\'\\\'\\\'');
+  return '\'\'\'' + string + '\'\'\'';
+};
+
+
 /**
  * Common tasks for generating Dart from blocks.
  * Handles comments for the specified block and any connected value blocks.