Incorrect syntax highlighting with YAML-multiline strings

[aeschli]

Steps to Reproduce:

1. Write YAML with multiline string, like this:

foo: bar
multiline: >
  This is a multiline string.
  This is still a multiline string, but has a colon: As you see, the syntax
  highlight doesn't work correctly as it thinks the text before colon is a key.
baz: quux

2. Save the YAML-file and notice the syntax highlight is incorrect:

Copied from original issue: microsoft/vscode#43827

[aeschli]

From @aripalo on February 16, 2018 13:26

Also same problem exists for multiline strings prefixed with pipe character |:

Input

foo: bar
multiline: |
  This is a multiline string.
  This is still a multiline string, but has a colon: As you see, the syntax
  highlight doesn't work correctly as it thinks the text before colon is a key.
baz: quux

Output:

[infininight]

Duplicate of #17. Slightly different trigger but the same cause, working to figure out a solution now.