v4.0.0

Commit	Message/Description
9cfb3a0	4.0.0
4b3bf2f	Test: add test for failures that have either stdout or stderr contents.
e905dff	On failure, print stdout if stderr is empty.
e7fe2d7	Test: nit-picking and cleanups.
0c7e57c	Test: fix .gitignore pattern for files created by "save-compiled-tests.js"
10e5ae8	CI: Add Node.js 10
38dfc20	Insert "use strict" directive
2a03496	Decrease timeout during testing
1108aab	Remove unnecessary test
bdfc8cd	Reorganize tests
db92d58	Integrate test262-stream
6f3dfca	Extend test coverage
9f09565	Re-organize tests
c38e31d	Add tests for file matching
27faffc	README: fix --saveCompiledTests to match CLI help