feat: allow to specify babelCore

Author: s-panferov

src/host.ts

@@ -44,6 +44,7 @@ export interface ICompilerOptions extends ts.CompilerOptions {
     forkChecker?: boolean;
     forkCheckerSilent?: boolean;
     useBabel?: boolean;
+    babelCore?: string;
     babelOptions?: any;
     usePrecompiledFiles?: boolean;
     skipDeclarationFilesCheck?: boolean;

src/instance.ts

@@ -199,7 +199,8 @@ export function ensureInstance(webpack: IWebPack, options: ICompilerOptions, ins
     let babelImpl: any;
     if (options.useBabel) {
         try {
-            babelImpl = require(path.join(process.cwd(), 'node_modules', 'babel-core'));
+            let babelPath = options.babelCore || path.join(process.cwd(), 'node_modules', 'babel-core');
+            babelImpl = require(babelPath);
         } catch (e) {
             console.error(BABEL_ERROR);
             process.exit(1);