Previous comment deleted (double checked, new results)

1. Synthetic scenario: http://output.jsbin.com/guyute#second

2. Real scenario: http://www.androidpolice.com/2016/03/21/supposed-developer-of-es-file-explorer-returns-with-fooview-a-floating-button-for-searching-screenshots-navigation-and-more/#comments

**Outcome**
Takeaway: 
 1. Better with Intervention: sticky anchoring on #second in the synthetic scenario (ignoring the known issue "off by 1px")

 2. unknown impact on real world scenario: I'm having a hard time getting a real scenario where the reflow(s) trigger after we've reached the fragment anchor... I'll try to find a way to hold the reflow triggering scripts a bit longer or find a different real world scenario.

I think fragment scrolling should create a scroll anchor for exactly the same reason that history restore should. The #2 real scenario above is a great case of why it's a better user experience.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/5114bd75de8b0e7813df98a6a2c9b43943cd4229

commit 5114bd75de8b0e7813df98a6a2c9b43943cd4229
Author: ymalik <ymalik@chromium.org>
Date: Thu Apr 28 20:36:16 2016

Test fragment scrolling and history restoration interaction w/ scroll anchoring.

This CL allows RuntimeEnabledFeatures with the option 'set_from_internals' to be set
from Internals. Previously, we could only read whether a feature was enabled.

The tests in this CL verify that we do scroll anchoring when a page has a fragment
and when doing history restoration.

Note that there are no behavioral changes in this CL.

BUG= 594880 , 594879 , 537764 

Review-Url: https://codereview.chromium.org/1895293002
Cr-Commit-Position: refs/heads/master@{#390463}

[add] https://crrev.com/5114bd75de8b0e7813df98a6a2c9b43943cd4229/third_party/WebKit/LayoutTests/fast/layout/scroll-anchoring/fragment-scrolling-anchors.html
[add] https://crrev.com/5114bd75de8b0e7813df98a6a2c9b43943cd4229/third_party/WebKit/LayoutTests/fast/layout/scroll-anchoring/history-restore-anchors.html
[modify] https://crrev.com/5114bd75de8b0e7813df98a6a2c9b43943cd4229/third_party/WebKit/Source/build/scripts/make_runtime_features.py
[modify] https://crrev.com/5114bd75de8b0e7813df98a6a2c9b43943cd4229/third_party/WebKit/Source/build/scripts/templates/InternalRuntimeFlags.h.tmpl
[modify] https://crrev.com/5114bd75de8b0e7813df98a6a2c9b43943cd4229/third_party/WebKit/Source/build/scripts/templates/InternalRuntimeFlags.idl.tmpl
[modify] https://crrev.com/5114bd75de8b0e7813df98a6a2c9b43943cd4229/third_party/WebKit/Source/platform/RuntimeEnabledFeatures.in