fix(wasm): keep imports

Author: xtuc

lib/wasm/WebAssemblyGenerator.js

@@ -282,9 +282,8 @@ const rewriteImports = ({ ast, usedDependencyMap }) => bin => {
 			const result = usedDependencyMap.get(
 				path.node.module + ":" + path.node.name
 			);
-			if (result === undefined) {
-				path.remove();
-			} else {
+
+			if (typeof result !== "undefined") {
 				path.node.module = WebAssemblyUtils.MANGLED_MODULE;
 				path.node.name = result.name;
 			}