DevTools: Add banks to JS sampling code map.

DevTools: Add banks to JS sampling code map.

The double type used to store addresses can hold exact numbers for
up to 2^53 (as this is the size of mantissa).
However raw frame addresses stored in V8 samples can be up to 64-bit
long.

The patch introduce banks to CodeMap. Raw address then split into bank
(upper 12 bits) and an address within the bank (lower 52 bits). This way
52-bit addresses can safely be stored in JS double type.

BUG=406277
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=197668

[alph, 2015-04-21 18:24:23]

alph@chromium.org changed reviewers:
+ yurys@chromium.org

[yurys, 2015-04-22 12:44:40]

Can we reuse codemap.js [1] (along with the splay tree implementation) from v8? 

[1]
https://code.google.com/p/chromium/codesearch#chromium/src/v8/tools/codemap.j...

[alph, 2015-06-22 15:52:51]

On 2015/04/22 12:44:40, yurys wrote:
> Can we reuse codemap.js [1] (along with the splay tree implementation) from
v8? 
> 
> [1]
>
https://code.google.com/p/chromium/codesearch#chromium/src/v8/tools/codemap.j...

We can't. The patch solves the problem that also exists in the code you pointed
out.

[yurys, 2015-06-22 16:33:00]

lgtm

https://codereview.chromium.org/1086083005/diff/20001/Source/devtools/front_e...
File Source/devtools/front_end/timeline/TimelineJSProfile.js (right):

https://codereview.chromium.org/1086083005/diff/20001/Source/devtools/front_e...
Source/devtools/front_end/timeline/TimelineJSProfile.js:290: var /** @const */
bankSizeHexDigits = 13;
Please extract these constants so that they are not duplicated.

[alph, 2015-06-23 16:06:28]

https://codereview.chromium.org/1086083005/diff/20001/Source/devtools/front_e...
File Source/devtools/front_end/timeline/TimelineJSProfile.js (right):

https://codereview.chromium.org/1086083005/diff/20001/Source/devtools/front_e...
Source/devtools/front_end/timeline/TimelineJSProfile.js:290: var /** @const */
bankSizeHexDigits = 13;
On 2015/06/22 16:33:00, yurys wrote:
> Please extract these constants so that they are not duplicated.

I'd like to keep them as constants for the sake of performance.

[alph, 2015-06-23 16:06:43]

The CQ bit was checked by alph@chromium.org

[commit-bot: I haz the power, 2015-06-23 16:07:09]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1086083005/20001

[commit-bot: I haz the power, 2015-06-23 18:55:55]

Committed patchset #2 (id:20001) as
https://src.chromium.org/viewvc/blink?view=rev&revision=197668