Remove unecessary check on Webpack version 4

Author: Kocal

lib/webpack-manifest-plugin/index.js

@@ -8,7 +8,6 @@
  */
 const { relative, resolve } = require('path');
 
-const webpack = require('webpack');
 const NormalModule = require('webpack/lib/NormalModule');
 
 const { beforeRunHook, emitHook, getCompilerHooks, normalModuleLoaderHook } = require('./hooks');
@@ -65,13 +64,9 @@ class WebpackManifestPlugin {
             hook.tap(hookOptions, normalModuleLoader);
         });
 
-        if (webpack.version.startsWith('4')) {
-            compiler.hooks.emit.tap(hookOptions, emit);
-        } else {
-            compiler.hooks.thisCompilation.tap(hookOptions, (compilation) => {
-                compilation.hooks.processAssets.tap(hookOptions, () => emit(compilation));
-            });
-        }
+        compiler.hooks.thisCompilation.tap(hookOptions, (compilation) => {
+            compilation.hooks.processAssets.tap(hookOptions, () => emit(compilation));
+        });
 
         compiler.hooks.run.tap(hookOptions, beforeRun);
         compiler.hooks.watchRun.tap(hookOptions, beforeRun);