Wrote test for img-src-4_1

http://www.w3.org/Security/wiki/Test_Assertions_For_Content_Security_Policy#Test_Assertions_for_img-src_directive
test for stylesheet load via link element being blocked if not in style-src
port existing php test over to new test harness
port existing php test for data: correctly allowing script in data: URIs to execute
port test for script-src 1.9 from php tests
start fleshing out some SRI tests
typo
Tests for AnimationNode attributes
Changes according the review notes
Different duration values added to the computedTiming test
Computed timing removed from this pull request
Add Event interface stub
Added --config option to serve.py.

In addition to reading the standard config.default.json file and any
config.json file in the working directory, this option allows you to
specify a custom location for any additional config file to read.
Meant to be useful for the case of, e.g., you don't want to have to keep
settings in a custom config.json in your working directory due to risk of
it getting blown away by a "git clean" or whatever.
Minor style tweak.
postMessage with zero or one argument shall throw SyntaxError

per the spec https://html.spec.whatwg.org/multipage/comms.html#dom-window-postmessage
fix structured-cloning with getter properties

Getter property would not be copied during structured-cloning, no Error
is mentioned in the spec (infrastructure.html#structured-clone). The
original case contained 2 independent cases, which can be separated.
Throw TypeError rather than SyntaxError

Thanks for @zcorpan review and comments as:

The algorithms in HTML are layered on top of WebIDL.
The input to the algorithms in HTML are IDL values.

https://html.spec.whatwg.org/multipage/browsers.html#window
 void postMessage(any message, DOMString targetOrigin, optional sequence<Transferable> transfer);

http://heycam.github.io/webidl/#es-operations
 Initialize S to the effective overload set for regular operations (if the operation is a regular operation)
 or for static operations (if the operation is a static operation) with identifier id on interface I and
 with argument count n.
 Let <operation, values> be the result of passing S and arg0..n−1 to the overload resolution algorithm.

http://heycam.github.io/webidl/#dfn-overload-resolution-algorithm
 When n = 0 or 1, step 4 throws TypeError.
Merge pull request #1435 from zqzhang/postMessage-exception

postMessage with zero or one argument shall throw SyntaxError
getter_cloning_should_propagate_exceptions

Agree with the reviewer's comment. Follow the steps defined in 8.2.
3rd param not Transferable should throw TypeError

- with-ports 025, 026 should throw TypeError when the 3rd param isn't
Transferable;
- without-ports 025, dont mean to fix the case. Remove the unused var
obj to avoid confusion in the future.