Fix project loading with bad text-number connections

Change-Id: I78c1666fd34346e46e68e112d02603e4de197fa5

appinventor/blocklyeditor/src/warningHandler.js

@@ -39,6 +39,15 @@ Blockly.WarningHandler.WarningState = {
   ERROR: 2
 };
 
+/**
+ * Regular expression for floating point numbers.
+ *
+ * @type {!RegExp}
+ * @const
+ */
+Blockly.WarningHandler.NUMBER_REGEX =
+  new RegExp("^[-+]?[0-9]*(\\.[0-9]+)?([eE][-+][0-9]+)?$")
+
 /**
  * The currently selected index into the array of block IDs with warnings. If nothing has been
  * selected (i.e., if we are not stepping through warnings), this should be -1 so that the next