build: Update various devDependencies to latest

grunt-jscs: 0.7.1 -> 0.8.1
karma: 0.12.23 -> 0.12.25
karma-chrome-launcher: 0.1.4 -> 0.1.5
qunit: 0.7.2 -> 0.7.5

No-op; note that the grunt-jscs change switches us from jscs 1.6.0 to
1.7.2, which provides some new options (unused in the Wikimedia preset).

Change-Id: I2784c1ed5340e8b4aaea639e736a1812a36e2610