Reset path bounding box tracking when starting a new path.

[brendandahl]

Starting a new path will wipe out any of the current subpaths in the
current graphics state, so we should reset the min/maxes.

This makes a number of the bounding boxes smaller and reduces the number
of composed pixels. For the smask tests in the corpus, the number of
composed pixesl goes from 19,872,109 to 19,676,905. The difference is much
larger on other PDFs though.

[brendandahl]

/botio test

[pdfjsbot]

From: Bot.io (Linux m4)

---

Received

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

Live output at: http://54.241.84.105:8877/c709132c568c0dc/output.txt

[pdfjsbot]

From: Bot.io (Windows)

---

Received

Command cmd_test from @brendandahl received. Current queue size: 1

Live output at: http://54.193.163.58:8877/72f6ac319682aa9/output.txt

[pdfjsbot]

From: Bot.io (Linux m4)

---

Failed

Full output at http://54.241.84.105:8877/c709132c568c0dc/output.txt

Total script time: 23.72 mins

• Font tests: Passed
• Unit tests: Passed
• Integration Tests: Passed
• Regression tests: FAILED

  different ref/snapshot: 8
  different first/second rendering: 2

Image differences available at: http://54.241.84.105:8877/c709132c568c0dc/reftest-analyzer.html#web=eq.log

[Snuffleupagus]

r=me, with passing tests; thank you!

[pdfjsbot]

From: Bot.io (Windows)

---

Failed

Full output at http://54.193.163.58:8877/72f6ac319682aa9/output.txt

Total script time: 33.08 mins

• Font tests: Passed
• Unit tests: Passed
• Integration Tests: Passed
• Regression tests: FAILED

  errors: 674
  different ref/snapshot: 3
  different first/second rendering: 2

Image differences available at: http://54.193.163.58:8877/72f6ac319682aa9/reftest-analyzer.html#web=eq.log

[Snuffleupagus]

/botio-windows browsertest

[pdfjsbot]

From: Bot.io (Windows)

---

Received

Command cmd_browsertest from @Snuffleupagus received. Current queue size: 1

Live output at: http://54.193.163.58:8877/2dda9084f86aca5/output.txt

[pdfjsbot]

From: Bot.io (Windows)

---

Failed

Full output at http://54.193.163.58:8877/2dda9084f86aca5/output.txt

Total script time: 38.03 mins

• Regression tests: FAILED

  different ref/snapshot: 9
  different first/second rendering: 1

Image differences available at: http://54.193.163.58:8877/2dda9084f86aca5/reftest-analyzer.html#web=eq.log