Implement ES2015 class feature (part I.) (#2404)

This patch is the first milestone of the implementation of this new language element.

Currently supported:
 - Class statement
 - Class expression
 - Static methods

JerryScript-DCO-1.0-Signed-off-by: Robert Fancsik frobert@inf.u-szeged.hu

jerry-core/api/jerry-snapshot.h

@@ -41,7 +41,7 @@ typedef struct
 /**
  * Jerry snapshot format version.
  */
-#define JERRY_SNAPSHOT_VERSION (14u)
+#define JERRY_SNAPSHOT_VERSION (15u)
 
 /**
  * Snapshot configuration flags.
@@ -50,6 +50,7 @@ typedef enum
 {
   /* 8 bits are reserved for dynamic features */
   JERRY_SNAPSHOT_HAS_REGEX_LITERAL = (1u << 0), /**< byte code has regex literal */
+  JERRY_SNAPSHOT_HAS_CLASS_LITERAL = (1u << 1), /**< byte code has class literal */
   /* 24 bits are reserved for compile time features */
   JERRY_SNAPSHOT_FOUR_BYTE_CPOINTER = (1u << 8) /**< compressed pointers are four byte long */
 } jerry_snapshot_global_flags_t;