diff --git a/.travis.yml b/.travis.yml
index 97239133d..d8635ec59 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -24,12 +24,12 @@ matrix:
     - node_js: 6
       os: windows # npm install --global currently fails on Windows. Skip the tests entirely instead.
 cache: npm
-before_install: if [[ $(node -pe "process.versions.node.split('.')[0]") == "6" ]]; then npm install --global npm@6; fi
+before_install: if [[ "$(npm -v)" != "6.6.0" ]] && [[ "${TRAVIS_OS_NAME}" != "windows" ]]; then npm install --global npm@6.6.0; fi
 install: npm ci
 before_script: |
   if [[ ${FRESH_DEPS} == "true" ]]; then
     npm install --no-shrinkwrap --prefer-online
-  else
+  elif [[ "${TRAVIS_OS_NAME}" != "windows" ]]; then
     checksum=$(md5sum package-lock.json)
     npm install --package-lock-only
     if ! echo ${checksum} | md5sum --quiet -c -; then
@@ -38,7 +38,7 @@ before_script: |
     fi
   fi
 
-  if [[ "${TRAVIS_OS_NAME}" == 'windows' ]]; then
+  if [[ "${TRAVIS_OS_NAME}" == "windows" ]]; then
     git config core.symlinks true
     git reset --hard
   fi
diff --git a/package-lock.json b/package-lock.json
index bd8a8c1e0..8b3890912 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -3452,7 +3452,8 @@
         },
         "ansi-regex": {
           "version": "2.1.1",
-          "bundled": true
+          "bundled": true,
+          "optional": true
         },
         "aproba": {
           "version": "1.2.0",
@@ -3470,11 +3471,13 @@
         },
         "balanced-match": {
           "version": "1.0.0",
-          "bundled": true
+          "bundled": true,
+          "optional": true
         },
         "brace-expansion": {
           "version": "1.1.11",
           "bundled": true,
+          "optional": true,
           "requires": {
             "balanced-match": "^1.0.0",
             "concat-map": "0.0.1"
@@ -3487,15 +3490,18 @@
         },
         "code-point-at": {
           "version": "1.1.0",
-          "bundled": true
+          "bundled": true,
+          "optional": true
         },
         "concat-map": {
           "version": "0.0.1",
-          "bundled": true
+          "bundled": true,
+          "optional": true
         },
         "console-control-strings": {
           "version": "1.1.0",
-          "bundled": true
+          "bundled": true,
+          "optional": true
         },
         "core-util-is": {
           "version": "1.0.2",
@@ -3598,7 +3604,8 @@
         },
         "inherits": {
           "version": "2.0.3",
-          "bundled": true
+          "bundled": true,
+          "optional": true
         },
         "ini": {
           "version": "1.3.5",
@@ -3608,6 +3615,7 @@
         "is-fullwidth-code-point": {
           "version": "1.0.0",
           "bundled": true,
+          "optional": true,
           "requires": {
             "number-is-nan": "^1.0.0"
           }
@@ -3620,17 +3628,20 @@
         "minimatch": {
           "version": "3.0.4",
           "bundled": true,
+          "optional": true,
           "requires": {
             "brace-expansion": "^1.1.7"
           }
         },
         "minimist": {
           "version": "0.0.8",
-          "bundled": true
+          "bundled": true,
+          "optional": true
         },
         "minipass": {
           "version": "2.2.4",
           "bundled": true,
+          "optional": true,
           "requires": {
             "safe-buffer": "^5.1.1",
             "yallist": "^3.0.0"
@@ -3647,6 +3658,7 @@
         "mkdirp": {
           "version": "0.5.1",
           "bundled": true,
+          "optional": true,
           "requires": {
             "minimist": "0.0.8"
           }
@@ -3719,7 +3731,8 @@
         },
         "number-is-nan": {
           "version": "1.0.1",
-          "bundled": true
+          "bundled": true,
+          "optional": true
         },
         "object-assign": {
           "version": "4.1.1",
@@ -3729,6 +3742,7 @@
         "once": {
           "version": "1.4.0",
           "bundled": true,
+          "optional": true,
           "requires": {
             "wrappy": "1"
           }
@@ -3804,7 +3818,8 @@
         },
         "safe-buffer": {
           "version": "5.1.1",
-          "bundled": true
+          "bundled": true,
+          "optional": true
         },
         "safer-buffer": {
           "version": "2.1.2",
@@ -3834,6 +3849,7 @@
         "string-width": {
           "version": "1.0.2",
           "bundled": true,
+          "optional": true,
           "requires": {
             "code-point-at": "^1.0.0",
             "is-fullwidth-code-point": "^1.0.0",
@@ -3851,6 +3867,7 @@
         "strip-ansi": {
           "version": "3.0.1",
           "bundled": true,
+          "optional": true,
           "requires": {
             "ansi-regex": "^2.0.0"
           }
@@ -3889,11 +3906,13 @@
         },
         "wrappy": {
           "version": "1.0.2",
-          "bundled": true
+          "bundled": true,
+          "optional": true
         },
         "yallist": {
           "version": "3.0.2",
-          "bundled": true
+          "bundled": true,
+          "optional": true
         }
       }
     },
@@ -5620,6 +5639,7 @@
           "version": "0.1.4",
           "bundled": true,
           "dev": true,
+          "optional": true,
           "requires": {
             "kind-of": "^3.0.2",
             "longest": "^1.0.1",
@@ -5944,7 +5964,8 @@
         "is-buffer": {
           "version": "1.1.6",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "is-builtin-module": {
           "version": "1.0.0",
@@ -6028,6 +6049,7 @@
           "version": "3.2.2",
           "bundled": true,
           "dev": true,
+          "optional": true,
           "requires": {
             "is-buffer": "^1.1.5"
           }
@@ -6074,7 +6096,8 @@
         "longest": {
           "version": "1.0.1",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "lru-cache": {
           "version": "4.1.3",
@@ -6340,7 +6363,8 @@
         "repeat-string": {
           "version": "1.6.1",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "require-directory": {
           "version": "2.1.1",
@@ -8664,6 +8688,7 @@
               "version": "0.1.4",
               "bundled": true,
               "dev": true,
+              "optional": true,
               "requires": {
                 "kind-of": "^3.0.2",
                 "longest": "^1.0.1",
@@ -9846,7 +9871,8 @@
             "longest": {
               "version": "1.0.1",
               "bundled": true,
-              "dev": true
+              "dev": true,
+              "optional": true
             },
             "loose-envify": {
               "version": "1.3.1",