From 090c364a90fe73d36a30707fc612ce037bdbbb24 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Sampo=20Kivist=C3=B6?= <sampo.kivisto@live.fi>
Date: Wed, 26 Sep 2018 23:16:40 +0300
Subject: [PATCH] Improved build performance by optimizing makeMappingKey
 method. (#8744)

---
 packages/babel-core/src/transformation/file/merge-map.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/babel-core/src/transformation/file/merge-map.js b/packages/babel-core/src/transformation/file/merge-map.js
index 991373862e1e..ff2e65b042b8 100644
--- a/packages/babel-core/src/transformation/file/merge-map.js
+++ b/packages/babel-core/src/transformation/file/merge-map.js
@@ -94,7 +94,7 @@ export default function mergeSourceMap(
 }
 
 function makeMappingKey(item: { line: number, columnStart: number }) {
-  return JSON.stringify([item.line, item.columnStart]);
+  return `${item.line}/${item.columnStart}`;
 }
 
 function eachOverlappingGeneratedOutputRange(