Fix Mocha tests.
Fix Mocha tests.

mark-friedman/blockly,nickmain/blockly,rachel-fenichel/blockly,rachel-fenichel/blockly,nickmain/blockly,rachel-fenichel/blockly,rachel-fenichel/blockly,nickmain/blockly,mark-friedman/blockly,rachel-fenichel/blockly,google/blockly,nickmain/blockly,picklesrus/blockly,google/blockly,nickmain/blockly,joshlory/blockly,google/blockly,nickmain/blockly,mark-friedman/blockly,mark-friedman/blockly,google/blockly,joshlory/blockly,joshlory/blockly,google/blockly,google/blockly,picklesrus/blockly,mark-friedman/blockly,rachel-fenichel/blockly,picklesrus/blockly,rachel-fenichel/blockly,google/blockly,mark-friedman/blockly