Same on linux. Works ok in Firefox.

Testcase: https://jsfiddle.net/d5k0ww3x/
Output: document.body.style.height=1.00099e+06px
Expected: document.body.style.height=1000990px

It looks like we store and print it as 'float', not an integer.
http://ideone.com/clFGOB

From the messages in https://codereview.chromium.org/1120133004 it sounds like other browsers already behave the same? Can someone document more rigorously how other browsers handle serialization?

CHANGELOG URL:
  https://chromium.googlesource.com/chromium/src/+log/c8cf02a2b8d39e0f70c255e4d68f51da2b39cc49..e72c28f23412e1fc1cf1fbd1a7275f7be9fe477d

Blink CL:
https://chromium.googlesource.com/chromium/blink/+log/c7ff1249d91d7a819cd82e0934a8b723c7ca6484..e1b16464d72188571e1328fc9c1719e04d0d3d2f

suspecting https://chromium.googlesource.com/chromium/blink/+/33f8fe1eef2a6f4c6c650834c2f9f45315924de7
rob.buis@, Could you please take a look at the issue and assign it to concerned developer if your changes are not responsible?

Good Build: 45.0.2408.0
Bad Build: 45.0.2410.0

Note: 
1. Able to reproduce the issue on Win7, Mac OSX 10.11.6, Ubuntu 14.04 using Chrome Stable 52.0.2743.116,Beta 53.0.2785.70, Dev 54.0.2832.2 and Canary 54.0.2835.0
2. Able to reproduce the issue using the testcase https://jsfiddle.net/d5k0ww3x/ (provided in c#3)
3. Before M45, in Chrome it is showing the value as document.body.style.height=1000988px (considered as good build)
4. Behaviour in other browsers
FF 47.0 : document.body.style.height=1000990px; IE 11 - document.body.style.height=1000988px; Safari 5.1.7 - document.body.style.height=1000988px

Pinging the owner asking to confirm whether their change caused this regression.

@9 yes, https://codereview.chromium.org/1120133004 caused an intentional change in behavior to be more spec compliant ("to not produce more than 6 decimals" spec addition).

Note that Firefox will start to have similar behavior at higher values:
> document.body.style.height = "9999995px";
> document.body.style.height
"1e+7px"

The cssom spec still says "Note: scientific notation is not used." for <number>.

 Issue 613527  has been merged into this issue.

Note also that https://codereview.chromium.org/1120133004 seems to cause style attributes to be formatted in a locale-dependent way (see also duped bug  http://crbug.com/620380 ). Rob, could you please update us with your progress? Thanks! 

It looks like I've decided to split this into two more specific bugs, one for the locale-dependent formatting (720222) and one for scientific notation (720225).