Fixed crash caused by certain pinned tabs - Pin tabs which are loaded causes a crash

[luixxiul]

Test plan

1. Clear your brave folder
2. Open https://github.com
3. Click the menu on the page to open 4 tabs
4. Pin all of them fast, before they are loaded completely
5. Make sure the browser does not crash

---

Describe the issue you encountered:
Pinning tabs which are loaded causes a crash.

• Platform (Win7, 8, 10? macOS? Linux distro?): WIndows 10 32 bit

• Brave Version (revision SHA): 0.13.3 RC1

• Steps to reproduce:

  1. Clear your brave folder
  2. Open https://github.com
  3. Click the menu on the page to open 4 tabs
  4. Pin all of them fast, before they are loaded completely

• Actual result: the browser crashes

• Expected result: the browser should not crash

• Will the steps above reproduce in a fresh profile? Yes

• Can this issue be consistently reproduced? Yes

• Extra QA steps:
  1.
  2.
  3.

• Any related issues:

[luixxiul]

If you pin tabs after they are loaded completely, the browser does not crash.

[cndouglas]

I can't reproduce with 0.13.2. Probably introduced during 0.13.3.

[bsclifton]

Moving to 0.14.1 (aka 0.13.7)

[bbondy]

I think this crash should be gone now
#8084

[luixxiul]

I cannot reproduce the error on the latest build.