Implement requests with partial file text to reduce memory usage for large files.

Add large comment to file1.js test file so it will be considered a large file and partial text updates can be tested.
For now, move two failing tests apart so they pass. Partial text updates are notas good a full text updates but save memory.
Merge pull request #4038 from dloverin/partial-updates

Implement requests with partial file text to reduce memory usage for large files