Fix search in pdf a containing some UTF-32 characters (bug 1820909)

[calixteman]

Some chars were supposed to have a length equals to 1 but UTF-32 chars can be longuer.

[Snuffleupagus]

r=me, thank you!

[calixteman]

/botio unittest

[pdfjsbot]

From: Bot.io (Linux m4)

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Received

Command cmd_unittest from @calixteman received. Current queue size: 0

Live output at: http://54.241.84.105:8877/dd9ff34de23e49a/output.txt

[pdfjsbot]

From: Bot.io (Linux m4)

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Success

Full output at http://54.241.84.105:8877/dd9ff34de23e49a/output.txt

Total script time: 2.52 mins

• Unit Tests: Passed

[calixteman]

/botio-windows unittest

[pdfjsbot]

From: Bot.io (Windows)

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Received

Command cmd_unittest from @calixteman received. Current queue size: 0

Live output at: http://54.193.163.58:8877/5ebed184be1fd48/output.txt

[pdfjsbot]

From: Bot.io (Windows)

---

Received

Command cmd_unittest from @calixteman received. Current queue size: 1

Live output at: http://54.193.163.58:8877/4d7a7a5a8d49f9c/output.txt

[pdfjsbot]

From: Bot.io (Windows)

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Failed

Full output at http://54.193.163.58:8877/5ebed184be1fd48/output.txt

Total script time: 10.82 mins

• Unit Tests: FAILED

[pdfjsbot]

From: Bot.io (Windows)

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Failed

Full output at http://54.193.163.58:8877/4d7a7a5a8d49f9c/output.txt

Total script time: 11.55 mins

• Unit Tests: FAILED

[calixteman]

/botio integrationtest

[pdfjsbot]

From: Bot.io (Linux m4)

---

Received

Command cmd_integrationtest from @calixteman received. Current queue size: 0

Live output at: http://54.241.84.105:8877/973f40eb4ce6eb2/output.txt

[pdfjsbot]

From: Bot.io (Windows)

---

Received

Command cmd_integrationtest from @calixteman received. Current queue size: 0

Live output at: http://54.193.163.58:8877/02613c6d9928d51/output.txt

[pdfjsbot]

From: Bot.io (Linux m4)

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Failed

Full output at http://54.241.84.105:8877/973f40eb4ce6eb2/output.txt

Total script time: 4.72 mins

• Integration Tests: FAILED

[pdfjsbot]

From: Bot.io (Windows)

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Failed

Full output at http://54.193.163.58:8877/02613c6d9928d51/output.txt

Total script time: 18.20 mins

• Integration Tests: FAILED