Update the keyboard navigation demo (#3785)
Update the keyboard navigation demo (#3785)


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