Improvements to JavaScript analysis

General improvements

Additional heuristics have been added to semmle.javascript.heuristics. Add import semmle.javascript.heuristics.all to a query in order to activate all of the heuristics at once.
Modelling of data flow through destructuring assignments has been improved. This may give additional results for the security queries and other queries that rely on data flow.
Support for popular libraries has been improved. Consequently, queries may produce more results on code bases that use the following libraries:
- bluebird
- browserid-crypto
- cookie-parser
- cookie-session
- crypto-js
- express-jwt
- express-session
- forge
- MySQL2
- q

Query	Tags	Purpose
Disabling Electron webSecurity (`js/disabling-electron-websecurity`)	security, frameworks/electron	Highlights Electron browser objects that are created with the `webSecurity` property set to false. Results shown on LGTM by default.
Enabling Electron allowRunningInsecureContent (`js/enabling-electron-insecure-content`)	security, frameworks/electron	Highlights Electron browser objects that are created with the `allowRunningInsecureContent` property set to true. Results shown on LGTM by default.
Use of externally-controlled format string (`js/tainted-format-string`)	security, external/cwe/cwe-134	Highlights format strings containing user-provided data, indicating a violation of CWE-134. Results shown on LGTM by default.

Query	Expected impact	Change
Arguments redefined	Fewer results	This rule previously also flagged redefinitions of `eval`. This was an oversight that is now fixed.
CORS misconfiguration for credentials transfer	More true-positive results	This rule now treats header names case-insensitively.
Hard-coded credentials	More true-positive results	This rule now recognizes secret cryptographic keys.
Insecure randomness	More true-positive results	This rule now recognizes secret cryptographic keys.
Missing X-Frame-Options HTTP header	Fewer false-positive results	This rule now treats header names case-insensitively.
Reflected cross-site scripting	Fewer false-positive results	This rule now treats header names case-insensitively.
Server-side URL redirect	More true-positive results	This rule now treats header names case-insensitively.
Uncontrolled command line	More true-positive results	This rule now recognizes indirect command injection through `sh -c` and similar.
Unused variable	Fewer results	This rule no longer flags class expressions that could be made anonymous. While technically true, these results are not interesting.

HTTP header names are now always normalized to lower case to reflect the fact that they are case insensitive. In particular, the result of HeaderDefinition.getAHeaderName, and the first parameter of HeaderDefinition.defines, ExplicitHeaderDefinition.definesExplicitly and RouteHandler.getAResponseHeader is now always a lower-case string.