Import emit fast where it's actually used

src/engine/target.js

@@ -9,6 +9,8 @@ const log = require('../util/log');
 const StringUtil = require('../util/string-util');
 const VariableUtil = require('../util/variable-util');
 
+require('../emit-fast');
+
 /**
  * @fileoverview
  * A Target is an abstract "code-running" object for the Scratch VM.

src/virtual-machine.js

@@ -24,7 +24,6 @@ const {loadCostume} = require('./import/load-costume.js');
 const {loadSound} = require('./import/load-sound.js');
 const {serializeSounds, serializeCostumes} = require('./serialization/serialize-assets');
 require('canvas-toBlob');
-require('./emit-fast');
 
 const RESERVED_NAMES = ['_mouse_', '_stage_', '_edge_', '_myself_', '_random_'];