flyout button stores all the deserialized properties (#4107)
flyout button stores all the deserialized properties (#4107)

The properties can be useful for callbacks, see https://github.com/google/blockly/issues/4027#issuecomment-656325534
rachel-fenichel/blockly,google/blockly,rachel-fenichel/blockly,mark-friedman/blockly,google/blockly,rachel-fenichel/blockly,google/blockly,mark-friedman/blockly,mark-friedman/blockly,mark-friedman/blockly,google/blockly,google/blockly,rachel-fenichel/blockly,mark-friedman/blockly,google/blockly,rachel-fenichel/blockly,rachel-fenichel/blockly,google/blockly,rachel-fenichel/blockly,mark-friedman/blockly