Tested the issue on Windows 7, Mac 10.11.5, Ubuntu 14.04 using 53.0.2756.0, latest dev 53.0.2763.0, canary 53.0.2764.0 with below steps:

1.Opened URL: https://jsfiddle.net/crl/1r0v702d/5/
2.Observed that the character 'w' font size after 'he' is small in chrome.
3.Observed that the character 'w' font size after 'he' is same in firefox.

Please find attached screenshots of chrome and firefox.

cyril.auburtin@Could you please provide expected behavior screenshot for further triaging the issue.

@ssamanoori I confirm the screenshots, Chrome adds inline style of the parent [contenteditable] element for some reason, thus makes the inserted 'w' smaller, this isn't expected in my opinion

Thank you for providing more feedback. Adding requester "ssamanoori@chromium.org" for another review and adding "Needs-Review" label for tracking.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

Able to reproduce the issue on Windows 7, Mac 10.11.5, Ubuntu 14.04 using 53.0.2756.0, latest dev 53.0.2767.4, beta 52.0.2743.41, stable 51.0.2704.84 as per steps in comment #1.

This is regression issue broken in M-49.

Please find below bisect info:
Last good build:49.0.2593.0
First bad build:49.0.2595.0

CHANGELOG URL:
https://chromium.googlesource.com/chromium/src/+log/3310eaa5df749be334db7c98e42e5c769deb88a1..34b7656997cd9f16639e10d7c67476b91b3a5aa0

From above CL, suspecting below:
https://chromium.googlesource.com/chromium/src/+/34b4044bbb07e2b911b6af2e85685f3ed22e2e8a

nhiroki@Could you please look into this issue if it is related to your change, else feel free to assign it to an appropriate dev person.

I think my change does not affect editing because it just replaced DCHECKs with CHECKs in service workers codebase and the example doesn't use service workers. Let me release this.

Following change is causing the issue
https://chromium.googlesource.com/chromium/src/+/2094957bd49cf75d7b8c8532114d815452ea515e

Moving this nonessential bug to the next milestone.

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This bug is tagged as regression.Which means that the bisects are incorrect or do not have an owner who is actively investigating.
Requesting the reporter to triage and update the behavior in all the latest chrome channels and bisect if needed.Close as WontFix if not reproducible.

This issue has been Available for over a year. If it's no longer important or seems unlikely to be fixed, please consider closing it out. If it is important, please re-triage the issue.

Sorry for the inconvenience if the bug really should have been left as Available.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot