Fix reading number of HTMX metrics.

[brendandahl]

The length of the HHEA table can be incorrect, so it is better to
read the number of metrics offset from beginning of table instead.

Fixes #10402

[brendandahl]

/botio test

[pdfjsbot]

From: Bot.io (Linux m4)

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Received

Command cmd_test from @brendandahl received. Current queue size: 0

Live output at: http://54.67.70.0:8877/ead6e65cd4d7ef1/output.txt

[pdfjsbot]

From: Bot.io (Windows)

---

Received

Command cmd_test from @brendandahl received. Current queue size: 0

Live output at: http://54.215.176.217:8877/51e57ef9904d458/output.txt

[pdfjsbot]

From: Bot.io (Linux m4)

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Success

Full output at http://54.67.70.0:8877/ead6e65cd4d7ef1/output.txt

Total script time: 17.50 mins

• Font tests: Passed
• Unit tests: Passed
• Regression tests: Passed

[pdfjsbot]

From: Bot.io (Windows)

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Success

Full output at http://54.215.176.217:8877/51e57ef9904d458/output.txt

Total script time: 23.40 mins

• Font tests: Passed
• Unit tests: Passed
• Regression tests: Passed

[timvandermeij]

/botio-linux preview

[pdfjsbot]

From: Bot.io (Linux m4)

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Received

Command cmd_preview from @timvandermeij received. Current queue size: 0

Live output at: http://54.67.70.0:8877/144ae5fb1a4e3cd/output.txt

[pdfjsbot]

From: Bot.io (Linux m4)

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Success

Full output at http://54.67.70.0:8877/144ae5fb1a4e3cd/output.txt

Total script time: 1.64 mins

Published

• Viewer: http://54.67.70.0:8877/144ae5fb1a4e3cd/web/viewer.html

[timvandermeij]

/botio makeref

[pdfjsbot]

From: Bot.io (Linux m4)

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Received

Command cmd_makeref from @timvandermeij received. Current queue size: 0

Live output at: http://54.67.70.0:8877/c1f16008fdfa9df/output.txt

[pdfjsbot]

From: Bot.io (Windows)

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Received

Command cmd_makeref from @timvandermeij received. Current queue size: 0

Live output at: http://54.215.176.217:8877/1c6d8697edd219d/output.txt

[pdfjsbot]

From: Bot.io (Linux m4)

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Success

Full output at http://54.67.70.0:8877/c1f16008fdfa9df/output.txt

Total script time: 16.08 mins

• Lint: Passed
• Make references: Passed
• Check references: Passed

[pdfjsbot]

From: Bot.io (Windows)

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Success

Full output at http://54.215.176.217:8877/1c6d8697edd219d/output.txt

Total script time: 20.99 mins

• Lint: Passed
• Make references: Passed
• Check references: Passed

[timvandermeij]

Nice work!