JSSpecCompiler: Add function call canonicalization pass

It simplifies ladders of BinaryOperators nodes in the function call
arguments into nice and neat FunctionCall node. Ladders initially appear
since I do not want to complicate expression parser, so it interprets
`f(a, b, c, d)` as `f "function_call_operator" (a, (b, (c, d))))`.

Meta/Lagom/Tools/CodeGenerators/JSSpecCompiler/CMakeLists.txt

@@ -1,6 +1,7 @@
 set(SOURCES
     AST/AST.cpp
     AST/ASTPrinting.cpp
+    Compiler/FunctionCallCanonicalizationPass.cpp
     Compiler/GenericASTPass.cpp
     Parser/Lexer.cpp
     Parser/ParseError.cpp