chrome canvas inspector 2015

Question

I used this nifty feature that chrome had for quite a while called \"canvas inspector\". It was an experimental dev feature that had to manually be enabled.

It was

Answer 1

Chrome and Firefox have both removed their Canvas inspectors...

Original Answer:
This is not exactly what the question asks for, but Firefox has a canvas inspector integrated: https://hacks.mozilla.org/2014/03/introducing-the-canvas-debugger-in-firefox-developer-tools/

You can enable it in the settings of the normal inspector

EDIT: (2019)
The Canvas Inspector has been removed as of Firefox 67:
Mozilla deprecated listing
Bug report with reasoning

Alternative:
spector.js - Recommended alternative by Mozilla