Fix missing requires in the insertion marker manager
Fix missing requires in the insertion marker manager

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