Clean up ./test directory

The with statement tests were novel, but the tests for
property accessors throwing errors for undefined & null
were duplicates with S11.2.1_A3_T4/5 respectively.

Add assert.throws

Closes #57.

add "assert.js" to python, website runners too

Initial assert helpers

Whitespace fixes

Presumably since Python is whitespace-sensitive, this is actually quite important?

Closes #110

Sbp_A1_T1 to Sbp_A5_T2, Sbp_12, Sbp_7*: Functions are now valid in blocks, tests syntactically invalid anyway
Sbp_A10_T1 to Sbp_A10_T2: Tests are broken

remove obsolete attributes from frontmatter fixes #80

browser runner: check negative regex

remove spec attribute
remove assertion, section, name

add initial set of tests for Promise

See also: https://github.com/tc39/test262/pull/29

test262.py crashes when --logfile due to reference to absent attribute 'logfile'

add test to repro #114
fix issue #114
factor out PercentFormat function
new fn write; start factoring summary output
fix tests to match
consolidate "Failed Tests" message
add test for successful run
consolidate all_succeeded message
consolidate summary line
consolidate ntests
failing negative tests
squeeze whitespace

add more tests of Promise.all

additional Promise test

add tests of Promise.prototype

add some tests for Promise.race

additional Promise tests

add Promise.reject and Promise.resolve tests

correct test description

rename badly-named files

use current license and minor style cleanup

correct understanding of undefined as thisArgument

incorporate line notes

Is this enough to make a constructor in ES6?

more accurate use of resolved,fulfilled etc.
remove some redundant tests
add new tests

remove "constant array" unclear language

better description

Update S25.4.2.1_A3.2_T1.js

address dangling ()

changes per @anba line notes
 - if GetIterator is abrupt, the Promise.race / Promise.all should reject
 - if Promise.race is called with nonconforming constructor as 'this',
   TypeError should be thrown (cannot reject if exeption is thrown from
   NewPromiseCapability; no promise exists yet...)

correct description of "this" testing in callbacks

fix whitespace, formatting

remove tab
add "next-turn" checking to sequencers

Use `target='_blank'` to open links in new window

load monkeyYaml without assuming it is on path

use imp to import monkeyYaml locally
make monkeyYaml the backup again

ES5.S15: new tests to clarify Array.prototype.concat

additional fixes suggested by @anba

remove spurious flags: [path]

provide fallback parser if YAML not installed

parseTestRecord.py:
- recover from ImportError when YAML not defined
- use monkeyYaml as backup

monkeyYaml.py:
- parser for subset of YAML used in test262 frontmatter

test_monkeyYaml.py:
- unit tests

document `timeout` and clean up