Update remaining NPM dependencies

DISABLE_THIRD_PARTY_CHECK=NPM fix
R=jacktfranklin@chromium.org

Bug: none
Change-Id: I41baa3294f88b7e4463fdc580c050932c5abe40e
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/3372932
Reviewed-by: Jack Franklin <jacktfranklin@chromium.org>
Commit-Queue: Tim Van der Lippe <tvanderlippe@chromium.org>
diff --git a/node_modules/convert-source-map/index.js b/node_modules/convert-source-map/index.js
index 3aeae10..d3265f0 100644
--- a/node_modules/convert-source-map/index.js
+++ b/node_modules/convert-source-map/index.js
@@ -18,7 +18,7 @@
 
 
 function decodeBase64(base64) {
-  return SafeBuffer.Buffer.from(base64, 'base64').toString();
+  return (SafeBuffer.Buffer.from(base64, 'base64') || "").toString();
 }
 
 function stripComment(sm) {
@@ -58,7 +58,7 @@
 
 Converter.prototype.toBase64 = function () {
   var json = this.toJSON();
-  return SafeBuffer.Buffer.from(json, 'utf8').toString('base64');
+  return (SafeBuffer.Buffer.from(json, 'utf8') || "").toString('base64');
 };
 
 Converter.prototype.toComment = function (options) {