Changed connections to handle disposing of connected blocks.

core/connection.js

@@ -233,15 +233,29 @@ Blockly.Connection.prototype.connect_ = function(childConnection) {
 };
 
 /**
- * Sever all links to this connection (not including from the source object).
+ * Dispose of this connection. Deal with connected blocks and remove this
+ * connection from the database.
  */
 Blockly.Connection.prototype.dispose = function() {
+
+  // isConnected returns true for shadows and non-shadows.
   if (this.isConnected()) {
-    throw Error('Disconnect connection before disposing of it.');
+    this.setShadowDom(null);
+    var targetBlock = this.targetBlock();
+    if (targetBlock.isShadow()) {
+      // Destroy the attached shadow block & its children.
+      targetBlock.dispose();
+    } else {
+      // Disconnect the attached normal block.
+      targetBlock.unplug();
+    }
   }
+
   if (this.inDB_) {
     this.db_.removeConnection_(this);
   }
+
+  this.disposed = true;
 };
 
 /**