Fixes pitch field not working with prompt

[BeksOmega]

The basics

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

The details

Resolves

Closes #4430
Related to google/blockly-games#212

Proposed Changes

Calls getValueFromEditorText_ before passing the value to setValue from the text input prompt editor (which is used on mobile).

I also got rid of the closure and used .bind() instead, as recommended by the styleguide.

Reason for Changes

Fixing bugs :D

Test Coverage

Could not reproduce google/blockly-games#212 using the following steps:

1. Change the text input field's show editor function to look like:

   Blockly.FieldTextInput.prototype.showEditor_ = function(_opt_e,
     opt_quietInput) {
     this.showPromptEditor_();
   };
   

2. Locally load the pitch field demo.
3. Enter the text "G4" into the prompt.
4. Hit "Ok".
5. Observe how the field has been properly updated.

Tested on:

• Desktop Chrome

Documentation

Nope!

Additional Information

N/A