Issue 6504 - Add useInlineStyles flag to ElemHideEmulation

With this flag the content script can ask ElemHideEmulation to always use CSS selectors for hiding.

We'll set this flag to false from the content script when both tabs.insertCSS and tabs.removeCSS are available and once the implementation on the ElemHideEmulation side is known to be stable. We need to make a few more optimizations for this case.

[Manish Jethani, 2018-03-02 13:55:21]

Patch Set 1

[Manish Jethani, 2018-03-05 13:31:48]

Patch Set 2: Change to ElemHideEmulation.useInlineStyles

[kzar, 2018-03-19 21:18:54]

LGTM but please can you split out the core changes into a separate blocking
issue? We're not allowed to land both core and platform changes in the same
issue. Also please check that Hubert's happy with the change before pushing
this.

https://codereview.adblockplus.org/29713583/diff/29714567/lib/content/elemHid...
File lib/content/elemHideEmulation.js (right):

https://codereview.adblockplus.org/29713583/diff/29714567/lib/content/elemHid...
lib/content/elemHideEmulation.js:419: this.useInlineStyles = true;
This doesn't match `alwaysHideWithSelector` in the issue description, please
could you update the description?

[Manish Jethani, 2018-03-20 11:20:23]

On 2018/03/19 21:18:54, kzar wrote:
> LGTM but please can you split out the core changes into a separate blocking
> issue? We're not allowed to land both core and platform changes in the same

Done.

https://issues.adblockplus.org/ticket/6504

> issue. Also please check that Hubert's happy with the change before pushing
> this.

I think this change should wait for all the changes for #6437.

https://codereview.adblockplus.org/29713583/diff/29714567/lib/content/elemHid...
File lib/content/elemHideEmulation.js (right):

https://codereview.adblockplus.org/29713583/diff/29714567/lib/content/elemHid...
lib/content/elemHideEmulation.js:419: this.useInlineStyles = true;
On 2018/03/19 21:18:54, kzar wrote:
> This doesn't match `alwaysHideWithSelector` in the issue description, please
> could you update the description?

Done.

[hub, 2018-03-20 13:04:58]

LGTM

[Manish Jethani, 2018-03-20 13:25:09]

On 2018/03/20 13:04:58, hub wrote:
> LGTM

Thanks.

On second thoughts, I'm going to go ahead and land this. Now since we're not
going to be doing a full DOM traversal on every mutation (various patches for
#6437), we'll have to keep the selectors up-to-date by writing some more code. I
can file a separate issue for that.

[Manish Jethani, 2018-03-20 13:36:16]

Patch Set 3: Rebase

[hub, 2018-03-20 13:39:54]

LGTM