http://test-results.appspot.com/dashboards/flakiness_dashboard.html#testType=webkit_tests&tests=sensor%2Fambient-light-sensor.html

It is occasionally failing on many platforms. Failures look like this:

CONSOLE INFO: line 30: Frequency is limited to 60 Hz.
CONSOLE INFO: line 53: Frequency is limited to 60 Hz.
This is a testharness.js-based test.
PASS Test that negative frequency causes exception from constructor. 
PASS Test that "onerror" is send when sensor is not supported. 
PASS Test that "onerror" is send when start() call has failed. 
PASS Test that frequency is capped to 60.0 Hz. 
PASS Test that frequency is capped to the maximum supported from frequency. 
PASS Test that sensor can be successfully created if sensor is supported. 
PASS Test that sensor can be constructed with default configuration. 
PASS Test that addConfiguration and removeConfiguration is called. 
PASS Test that onChange is called and sensor reading is valid (onchange reporting). 
PASS Test that onChange is called and sensor reading is valid (continuous reporting). 
PASS Test that sensor receives suspend / resume notifications when page visibility changes. 
PASS Test that sensor reading is correct. 
PASS Test that frequency hint works (onchange reporting). 
FAIL Test that frequency hint works (continuous reporting). promise_test: Unhandled rejection with value: undefined
Harness: the test ran to completion.

In other words, the last test occasionally fails.