fix: playground test blocks, text area listeners, and show/hide buttons (#6015)
fix: playground test blocks, text area listeners, and show/hide buttons (#6015)


google/blockly,mark-friedman/blockly,rachel-fenichel/blockly,rachel-fenichel/blockly,mark-friedman/blockly,mark-friedman/blockly,rachel-fenichel/blockly,mark-friedman/blockly,mark-friedman/blockly,google/blockly,rachel-fenichel/blockly,google/blockly,google/blockly,rachel-fenichel/blockly,rachel-fenichel/blockly,google/blockly,mark-friedman/blockly,google/blockly,google/blockly,rachel-fenichel/blockly