[Truffle] Fixed String.split(Regexp) without a limit.

Prior to this change trailing empty fields weren't being suppressed.

Author: nirvdrum

spec/truffle/tags/core/string/split_tags.txt

@@ -12,7 +12,6 @@ fails:String#split with String tries converting limit to an integer via to_int
 fails:String#split with String returns subclass instances based on self
 fails:String#split with String does not call constructor on created subclass instances
 fails:String#split with String taints the resulting strings if self is tainted
-fails:String#split with Regexp suppresses trailing empty fields when limit isn't given or 0
 fails:String#split with Regexp defaults to $; when regexp isn't given or nil
 fails:String#split with Regexp includes all captures in the result array
 fails:String#split with Regexp does not include non-matching captures in the result array
@@ -24,4 +23,3 @@ fails:String#split with Regexp taints an empty string if self is tainted
 fails:String#split with Regexp retains the encoding of the source string
 fails:String#split with Regexp splits a string on each character for a multibyte encoding and empty split
 fails:String#split with Regexp returns an ArgumentError if an invalid UTF-8 string is supplied
-fails:String#split with Regexp doesn't taints the resulting strings if the Regexp is tainted

truffle/src/main/java/org/jruby/truffle/runtime/core/RubyRegexp.java

@@ -324,6 +324,13 @@ public RubyString[] split(final RubyString string, final boolean useLimit, final
             }
         }
 
+        // Suppress trailing empty fields if not using a limit and the supplied limit isn't negative.
+        if (!useLimit && limit == 0) {
+            while (! strings.isEmpty() && (strings.get(strings.size() - 1).length() == 0)) {
+                strings.remove(strings.size() - 1);
+            }
+        }
+
         return strings.toArray(new RubyString[strings.size()]);
     }