Revert of DevTools: [SSP] adding new property should be more predictable

Revert of DevTools: [SSP] adding new property should be more predictable (patchset #2 id:20001 of https://codereview.chromium.org/1433903002/ )

Reason for revert:
This patch makes selecting properties in SSP tedious.
Example:
1. try selecting all properties of some rule
2. left-click in the empty space of the rule does not always removes selection

Original issue's description:
> DevTools: [SSP] adding new property should be more predictable
>
> Whitelist selectable elements to avoid excessive text "selectability".
>
> BUG=554454
> R=pfeldman, dgozman
>
> Committed: https://crrev.com/491172b142d4b302674c4552eea14cecd0421dbc
> Cr-Commit-Position: refs/heads/master@{#360494}

TBR=dgozman@chromium.org,pfeldman@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=554454
Committed: https://crrev.com/d4d928857ead303fd863e7f97a4f3f22f880dd07
Cr-Commit-Position: refs/heads/master@{#360698}

[lushnikov, 2015-11-20 00:33:34]

Created Revert of DevTools: [SSP] adding new property should be more predictable

[commit-bot: I haz the power, 2015-11-20 00:36:20]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1465713002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1465713002/1

[commit-bot: I haz the power, 2015-11-20 00:40:34]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-11-20 00:50:06]

Patchset 1 (id:??) landed as
https://crrev.com/d4d928857ead303fd863e7f97a4f3f22f880dd07
Cr-Commit-Position: refs/heads/master@{#360698}