JS inline: added test utils
JS inline: removed legacy inline tests
JS backend: JS AST access from tests
JS inline: added inline tests
JS inline: imported inline tests from JVM-backend
JS backend: added visitors with context
JS inline: removed legacy inline logic
JS inline: pass call expression to InlinedCallExpressionTranslator
JS backend: break label should be JsNameRef, not String

The reason is to make it easier to distinguish
between different break labels (that's valid on same level).
JsNameRefs can be distinguished by their JsName.
JS inline: added CloningVisitor
JS inline: added InlineableResult
JS inline: added FunctionInlineMutator
JS inline: added JsInliner
JS inline: save static ref to JsFunction in JsName
JS inline: collect defined functions
JS inline: save inline status during translation
JS inline: inline function calls
JS inline: run JsInliner after AST is built
JS backend: made JsInvocation arguments modifieable
JS backend: made JsBlock statements list modifieable