Fix connection DB bug when workspace contains blocks with errors

Change-Id: I47f76f80ac48b37f2fb9bc82c174021fb918da0f

appinventor/blocklyeditor/src/connection_db.js

@@ -78,3 +78,15 @@ Blockly.ConnectionDB.prototype.removeConnection_ = function(connection) {
    this.splice(removalIndex, 1);
  }
};

/**
 * O(n) removal of duplicate connections.
 */
Blockly.ConnectionDB.prototype.removeDupes = function() {
  for (var i = 0; i < this.length - 1; i++) {
    if (this[i] == this[i+1]) {
      this.splice(i, 1);
      i--;
    }
  }
};

appinventor/blocklyeditor/src/workspace_svg.js

@@ -1063,6 +1063,13 @@ Blockly.WorkspaceSvg.prototype.sortConnectionDB = function() {
    connectionDB.sort(function(a, b) {
      return a.y_ - b.y_;
    });
    // If we are rerendering due to a new error, we only redraw the error block, which means that
    // we can't clear the database, otherwise all other connections disappear. Instead, we add
    // the moved connections anyway, and at this point we can remove the duplicate entries in the
    // database. We remove after sorting so that the operation is O(n) rather than O(n^2). This
    // assumption may break in the future if Blockly decides on a different mechanism for indexing
    // connections.
    connectionDB.removeDupes();
  });
};