Able to reproduce the issue on Mac OS 10.11.6 using chrome latest Dev M55-55.0.2872.0 by following steps mentioned in the original comment. 

Using the per-revision bisect providing the bisect results,
Good build:55.0.2862.0(Revision: 419063).
Bad build:55.0.2863.0(Revision: 419330).

You are probably looking for a change made after 419304 (known good), but no later than 419305 (first known bad).

CHANGELOG URL:
https://chromium.googlesource.com/chromium/src/+log/e0f27b9808ea6a7333669e2404be671fd4231d00..fd9f42976b2d7c512f5242dffe713bfa06c22a9c

From the CL above, assigning the issue to the concern owner 

@einbinder- Could you please check whether this is caused with respect to your change, if not please help us in assigning it to the right owner.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/9926833faef089c9f45c303a0e0664083b0f64ad

commit 9926833faef089c9f45c303a0e0664083b0f64ad
Author: einbinder <einbinder@chromium.org>
Date: Tue Sep 27 03:04:29 2016

DevTools: Move "enter" logic from ConsoleView to ConsolePrompt
Also fixes a bug where enter was never captured by the SuggestBox.

BUG= 650155 

Review-Url: https://codereview.chromium.org/2361273002
Cr-Commit-Position: refs/heads/master@{#421088}

[modify] https://crrev.com/9926833faef089c9f45c303a0e0664083b0f64ad/third_party/WebKit/LayoutTests/http/tests/inspector/console-test.js
[modify] https://crrev.com/9926833faef089c9f45c303a0e0664083b0f64ad/third_party/WebKit/LayoutTests/inspector/console/console-smart-enter-expected.txt
[modify] https://crrev.com/9926833faef089c9f45c303a0e0664083b0f64ad/third_party/WebKit/LayoutTests/inspector/console/console-smart-enter.html
[modify] https://crrev.com/9926833faef089c9f45c303a0e0664083b0f64ad/third_party/WebKit/Source/devtools/front_end/Tests.js
[modify] https://crrev.com/9926833faef089c9f45c303a0e0664083b0f64ad/third_party/WebKit/Source/devtools/front_end/console/ConsolePrompt.js
[modify] https://crrev.com/9926833faef089c9f45c303a0e0664083b0f64ad/third_party/WebKit/Source/devtools/front_end/console/ConsoleView.js

Issue is working fine in 55.0.2875.0 dev of Linux and Windows. i.e; Selected word from suggest box shows up in console prompt.

The same is working fine on the latest canary(55.0.2875.0) on Mac OS 10.11.6 as well. Hence adding the verified label.

Closing the issue as Fixed as this is verified as per C#3 and C#4. Please reopen if there is any further work to be done here.

Thank you! 

[Auto-generated comment by a script] We noticed that this issue is targeted for M-55; it appears the fix may have landed after branch point, meaning a merge might be required. Please confirm if a merge is required here - if so add Merge-Request-55 label, otherwise remove Merge-TBD label. Thanks.

No merge is needed for M55.