Allow to use dynamic types for JS projects in IDEA.
Frontend: add default getter and setter to dynamic property descriptors.
Frontend: add JetTokens.EQEQEQ and JetTokens.EXCLEQEQEQ to OperatorConventions.NOT_OVERLOADABLE
Minor in JS AST: drop unused constructors from JsBinaryOperation, JsUnaryOperation, JsPrefixOperation and JsPostfixOperation.
JS backend: fix "is Boolean" check.
Minor in JS backend: save operation token as member of BinaryOperationTranslator.
Minor in JS backend: simplify CompareToBOIF::getIntrinsic.
JS backend: added the support dynamic.
JS frontend: introduce some JavaScript specific constants.
JS tests: added doTest and checkFooBoxIsOkByPath to BasicTest to simplify using generated tests.
JS tests: use js files from some places by default:

* add all js files from testData/_commonFiles
* add all js files from <testDir>/_commonFiles
* add <testDir>/cases/<testName>.js if it exists
JS tests: added tests for dynamic.
JS backend: use special JsScope(JsDynamicScope) for names from dynamic calls instead of use containing scope to avoid the impact on local names.