Add support for beginless ranges in caller and backtrace

src/main/ruby/truffleruby/core/kernel.rb

@@ -726,17 +726,13 @@ def printf(*args)
   end
 
   def caller(start = 1, limit = nil)
-    args = if start.is_a? Range
-             if Primitive.nil? start.end
-               [start.begin + 1]
-             else
-               [start.begin + 1, start.size]
-             end
-           elsif Primitive.nil? limit
-             [start + 1]
-           else
-             [start + 1, limit]
-           end
+    args =  if start.is_a? Range
+              [start] # handled by caller_locations
+            elsif Primitive.nil? limit
+              [start + 1]
+            else
+              [start + 1, limit]
+            end
     Kernel.caller_locations(*args).map(&:to_s)
   end
   module_function :caller

src/main/ruby/truffleruby/core/truffle/kernel_operations.rb

@@ -181,7 +181,11 @@ def self.normalize_backtrace_args(omit, length)
       end
       if Range === omit
         range = omit
-        omit = Primitive.rb_to_int(range.begin)
+        if Primitive.nil? range.begin
+          omit = 0
+        else
+          omit = Primitive.rb_to_int(range.begin)
+        end
         unless Primitive.nil? range.end
           end_index = Primitive.rb_to_int(range.end)
           if end_index < 0