Added FinishedLoading Event

[BeksOmega]

The basics

• I branched from develop
• My pull request is against develop
• My code follows the style guide

The details

Resolves

Proposed Changes

#2142

Reason for Changes

Quote from Issue:

Developers sometimes want to run some actions after a workspace finishes loading. There is no event to indicate this right now.

Test Coverage

1 . Turned on "Log events" in the playground.
2 . Hit the "Spaghetti" button.
3 . Observed how a FinishedLoading event was correctly fired. (pass)

1 . Changed the following code ~ln 251 in playground:

  console.time('Spaghetti domToWorkspace');
  Blockly.Xml.domToWorkspace(dom, workspace);
  console.timeEnd('Spaghetti domToWorkspace');

To:

 console.time('Spaghetti domToWorkspace');
 Blockly.Events.setGroup(true);
 console.log(Blockly.Events.group_);
 Blockly.Xml.domToWorkspace(dom, workspace);
 Blockly.Events.setGroup(false);
 console.timeEnd('Spaghetti domToWorkspace');

2 . Hit the "Spaghetti" button.
3 . Observed how a FinishedLoading event (with the correct group) was fired. (pass)

1 . Added the following code at ~ln 256 in playground (at the top of the spaghettiXml var):
' <shadow type="controsl_if"></shadow>',
2 . Hit the "Spaghetti" button.
3 . Observed how the FinishedLoading event was not fired, because an error was thrown. (pass)

Tested on:

• Desktop Chrome

Additional Information

I'm not sure the FinishedLoading event needed to be in a new file, but I couldn't decide where else to put it. If it does need to be in a new file, I'm not sure if the copyright should be updated to 2019 or not.

[rachel-fenichel]

Add a goog.require for Blockly.Events.FinishedLoading at the top of this file.

[rachel-fenichel]

Update this and line 88 to be Blockly.Events.FinishedLoading instead of Blockly.Events.Ui