Define Kernel#global_variables directly with a @coremethod

Author: eregon

src/main/java/org/truffleruby/core/kernel/KernelNodes.java

@@ -1792,8 +1792,8 @@ protected boolean isDebug(VirtualFrame frame) {
 
     }
 
-    @Primitive(name = "kernel_global_variables", needsSelf = false)
-    public abstract static class KernelGlobalVariablesPrimitiveNode extends PrimitiveArrayArgumentsNode {
+    @CoreMethod(names = "global_variables", isModuleFunction = true)
+    public abstract static class KernelGlobalVariablesNode extends CoreMethodArrayArgumentsNode {
 
         @TruffleBoundary
         @Specialization

src/main/ruby/core/kernel.rb

@@ -615,12 +615,6 @@ def at_exit(&block)
   end
   module_function :at_exit
 
-  def global_variables
-    Truffle.primitive :kernel_global_variables
-    raise PrimitiveFailure, 'Kernel.global_variables primitive failed'
-  end
-  module_function :global_variables
-
   def fork
     raise NotImplementedError, 'fork is not available'
   end