Upgrade webpack 2 (#4748)

* update webpack to version 4

* repair build bug

* update package code

* optimize package script

* update seafile-editor version

* repair code bug

frontend/config/jest/fileTransform.js

@@ -1,12 +1,40 @@
 'use strict';
 
 const path = require('path');
+const camelcase = require('camelcase');
 
 // This is a custom Jest transformer turning file imports into filenames.
 // http://facebook.github.io/jest/docs/en/webpack.html
 
 module.exports = {
   process(src, filename) {
-    return `module.exports = ${JSON.stringify(path.basename(filename))};`;
+    const assetFilename = JSON.stringify(path.basename(filename));
+
+    if (filename.match(/\.svg$/)) {
+      // Based on how SVGR generates a component name:
+      // https://github.com/smooth-code/svgr/blob/01b194cf967347d43d4cbe6b434404731b87cf27/packages/core/src/state.js#L6
+      const pascalCaseFilename = camelcase(path.parse(filename).name, {
+        pascalCase: true,
+      });
+      const componentName = `Svg${pascalCaseFilename}`;
+      return `const React = require('react');
+      module.exports = {
+        __esModule: true,
+        default: ${assetFilename},
+        ReactComponent: React.forwardRef(function ${componentName}(props, ref) {
+          return {
+            $$typeof: Symbol.for('react.element'),
+            type: 'svg',
+            ref: ref,
+            key: null,
+            props: Object.assign({}, props, {
+              children: ${assetFilename}
+            })
+          };
+        }),
+      };`;
+    }
+
+    return `module.exports = ${assetFilename};`;
   },
 };