dependencies: Use patched source-map with a performance fix.

mozilla/source-map#370

This makes Webpack about 9% faster.  Before:

$ multitime -n9 -s0 node_modules/.bin/webpack --config-name=frontend --display=errors-only -p
===> multitime results
1: node_modules/.bin/webpack --config-name=frontend --display=errors-only -p
            Mean        Std.Dev.    Min         Median      Max
real        18.243      0.107       18.090      18.236      18.443
user        27.913      0.188       27.714      27.843      28.251
sys         2.028       0.043       1.933       2.039       2.074

After:

$ multitime -n9 -s0 node_modules/.bin/webpack --config-name=frontend --display=errors-only -p
===> multitime results
1: node_modules/.bin/webpack --config-name=frontend --display=errors-only -p
            Mean        Std.Dev.    Min         Median      Max
real        16.686      0.085       16.542      16.684      16.885
user        25.965      0.167       25.559      26.022      26.163
sys         1.965       0.064       1.807       1.998       2.010

Signed-off-by: Anders Kaseorg <anders@zulipchat.com>

package.json

@@ -99,7 +99,7 @@
     "prettier": "^2.0.5",
     "puppeteer": "^5.2.0",
     "rewiremock": "^3.13.9",
-    "source-map": "^0.6.1",
+    "source-map": "https://github.com/benthemonkey/source-map.git#d95423f77edef6cbb9e21d2d6014c7de85ae220a",
     "stylelint": "^13.0.0",
     "stylelint-config-prettier": "^8.0.2",
     "stylelint-config-standard": "^20.0.0",
@@ -111,6 +111,9 @@
     "yarn-deduplicate": "^3.0.0",
     "zulip-js": "^2.0.8"
   },
+  "resolutions": {
+    "/source-map": "https://github.com/benthemonkey/source-map.git#d95423f77edef6cbb9e21d2d6014c7de85ae220a"
+  },
   "scripts": {
     "postinstall": "rm -rf ./var/webpack-cache",
     "lint": "eslint --quiet --cache",

version.py

@@ -44,4 +44,4 @@
 #   historical commits sharing the same major version, in which case a
 #   minor version bump suffices.
 
-PROVISION_VERSION = '111.2'
+PROVISION_VERSION = '111.3'

yarn.lock

@@ -11002,10 +11002,9 @@ source-map@^0.5.0, source-map@^0.5.6:
   resolved "https://registry.yarnpkg.com/source-map/-/source-map-0.5.7.tgz#8a039d2d1021d22d1ea14c80d8ea468ba2ef3fcc"
   integrity sha1-igOdLRAh0i0eoUyA2OpGi6LvP8w=
 
-source-map@^0.6.0, source-map@^0.6.1, source-map@~0.6.0, source-map@~0.6.1:
+source-map@^0.6.0, source-map@^0.6.1, "source-map@https://github.com/benthemonkey/source-map.git#d95423f77edef6cbb9e21d2d6014c7de85ae220a", source-map@~0.6.0, source-map@~0.6.1:
   version "0.6.1"
-  resolved "https://registry.yarnpkg.com/source-map/-/source-map-0.6.1.tgz#74722af32e9614e9c287a8d0bbde48b5e2f1a263"
-  integrity sha512-UjgapumWlbMhkBgzT7Ykc5YXUT46F0iKu8SGXq0bcwP5dz/h0Plj6enJqjz1Zbq2l5WaqYnrVbwWOWMyF3F47g==
+  resolved "https://github.com/benthemonkey/source-map.git#d95423f77edef6cbb9e21d2d6014c7de85ae220a"
 
 source-map@^0.7.3:
   version "0.7.3"