CP-958 Prevent pub serve errors from examples task

[maxwellpeterson-wf]

Issue

Fix #52

Currently if pub serve has any output on stderr during the examples task, it will cause the dart_dev process to exit. This happens any time there is a dart2js warning, or even a 404 (even for favicon.ico!)

Changes

Source:

• Expose additional output stream for pubServeStdErr from ExamplesTask
• Log pubSeveStdErr as the error stream, making it yellow. Screenshot:

Areas of Regression

• None, bugfix only.

Testing

• Target this version of dart_dev in some project that uses it and has examples
• Run pub run dart_dev examples
• In the browser, cause a 404. A force refresh would request the favicon.ico, for example.
• Pub serve should continue running after the 404, and the 404 should show up as yellow in the console like the screenshot above.

@trentgrover-wf
@evanweible-wf
@dustinlessard-wf
FYI @jayudey-wf

[codecov-io]

Current coverage is 48.05%

Merging #68 into master will not affect coverage as of 1e4577b

Powered by Codecov. Updated on successful CI builds.

[evanweible-wf]

+1

[trentgrover-wf]

+1
@jayudey-wf ready for merge

[jayudey-wf]

QA Resource Approval: +10

• Testing instruction
• Dev +1's
• Dev/QA +10 with detail of what was tested
  • verified that 404 was presented in the console in yellow and that the server was not halted
• Unit test created/updated
• All unit tests pass

Merging into master.