[js] Remove code to handle v8 < 5.0

We require at least node v6 which means v8 5.0, so code to handle
older v8 is no longer useful.

Lib/javascript/v8/javascriptruntime.swg

@@ -7,36 +7,8 @@
 // ----------------
 //
 // v8 added version macros V8_MAJOR_VERSION, V8_MINOR_VERSION, V8_BUILD_NUMBER
-// and V8_PATCH_LEVEL in version 4.3.0.  SWIG generated code uses these if
-// they are defined - to support earlier versions you can specify the V8 version
-// in use via the command line when you run SWIG:
-//
-//   swig -c++ -javascript -v8 -DV8_VERSION=0x032530 example.i
-//
-// Or code in the interface file using SWIG_V8_VERSION:
-//
-//   %begin %{#define SWIG_V8_VERSION 0x031110%}
-//
-// This is specified as a hex constant, but the constant is read as pairs of
-// decimal digits, so for V8 3.25.30 use constant 0x032530.  This scheme can't
-// represent components > 99, but this constant is only useful for V8 < 4.3.0,
-// and no V8 versions from that era had a component > 99.
-
-%define %swig_v8_define_version(version)
-%insert("runtime") %{
-#ifndef SWIG_V8_VERSION
-#define SWIG_V8_VERSION version
-#endif
-%}
-%enddef
-
-#ifdef V8_VERSION
-%swig_v8_define_version(V8_VERSION)
-#else
-// HACK: defining a default version
-%swig_v8_define_version(0x031110)
-#endif
-
+// and V8_PATCH_LEVEL in version 4.3.0.  SWIG doesn't support anything that
+// old so SWIG generated code can rely on these.
 
 // Node support
 // ------------
@@ -56,13 +28,11 @@
 %insert(runtime) %{
 #include <v8.h>
 
-#if defined(V8_MAJOR_VERSION) && defined(V8_MINOR_VERSION)
 #undef SWIG_V8_VERSION
 #define SWIG_V8_VERSION ((V8_MAJOR_VERSION / 10) * 4096 + \
                          (V8_MAJOR_VERSION % 10) * 256 + \
                          (V8_MINOR_VERSION / 10) * 16 + \
                          (V8_MINOR_VERSION % 10))
-#endif
 
 #include <errno.h>
 #include <limits.h>