Pin dependencies

[renovate]

This PR contains the following updates:

Package	Type	Update	Change
babel-core (source)	devDependencies	pin	^6.26.0 -> 6.26.3
babel-loader	devDependencies	pin	^7.1.2 -> 7.1.5
babel-preset-es2015 (source)	devDependencies	pin	^6.24.1 -> 6.24.1
eslint (source)	devDependencies	pin	^4.16.0 -> 4.19.1
eslint-config-google	devDependencies	pin	^0.9.1 -> 0.9.1
jsonlint (source)	dependencies	pin	~1.6.2 -> 1.6.3
mocha (source)	devDependencies	pin	~2.2.4 -> 2.2.5
serve	devDependencies	pin	^6.4.9 -> 6.5.8
webpack	devDependencies	pin	^3.10.0 -> 3.12.0

📌 Important: Renovate will wait until you have merged this Pin PR before creating any upgrade PRs for the affected packages. Add the preset :preserveSemverRanges your config if you instead don't wish to pin dependencies.

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