Port npm update task.

Makefile

@@ -14,7 +14,7 @@ else
   ESC_DOLLAR = \$$
 endif
 
-npgoals := clean cleanrel cleanweb cleanfull tag $(foreach i,1 2 3 4,bump$(i)) beta stable web
+npgoals := clean cleanrel cleanweb cleanfull tag $(foreach i,1 2 3 4,bump$(i)) beta stable web update
 ifneq "$(filter $(npgoals),$(MAKECMDGOALS))" ""
 .NOTPARALLEL :
 endif
@@ -309,3 +309,7 @@ web : index.html distready
 	cd dist && git merge --no-commit -s ours master
 	cd dist && git checkout master README.md index.html web.css img
 	cd dist && git commit -am "Update web page."
+
+update :
+	npm install --save-dev $(shell node tools/unpinned.js)
+	npm shrinkwrap --dev

tools/unpinned.js

@@ -0,0 +1,11 @@
+var fs = require('fs');
+
+var pkg = JSON.parse(fs.readFileSync('package.json', 'utf8'));
+
+console.log(
+  Object.keys(pkg.devDependencies).filter(
+    name => /^\^/.test(pkg.devDependencies[name])
+  ).map(
+    name => `${name}@latest`
+  ).join(' ')
+);