Updates after upstream/master rebase

Author: ViktorHofer

src/System.Text.RegularExpressions/src/System/Buffers/MemoryOrPinnedSpan.cs

@@ -21,6 +21,7 @@ public MemoryOrPinnedSpan(char* pinnedSpan, int length)
         {
             _ptr = pinnedSpan;
             _length = length;
+            _memory = null;
         }
 
         public int Length => _length;

src/System.Text.RegularExpressions/src/System/Text/RegularExpressions/GroupCollection.cs

@@ -224,7 +224,7 @@ public bool TryGetValue(string key, out Group value)
 
         public bool ContainsKey(string key)
         {
-            return _match._regex.GroupNumberFromName(key) >= 0;
+            return _match.Regex.GroupNumberFromName(key) >= 0;
         }
 
         public IEnumerable<string> Keys

src/System.Text.RegularExpressions/src/System/Text/RegularExpressions/Regex.Split.cs

@@ -187,6 +187,7 @@ internal SplitEnumerator(Regex regex, ReadOnlySpan<char> input, int count)
                 _match = null;
                 _inputIndex = _regex.RightToLeft ? input.Length : 0;
                 _groupIndex = 1;
+                Current = null;
             }
 
             /// <summary>

src/System.Text.RegularExpressions/tests/Regex.Match.Tests.cs

@@ -858,26 +858,7 @@ public void Match_Invalid()
             AssertExtensions.Throws<ArgumentOutOfRangeException>("length", () => new Regex("pattern").Match("input", 0, -1));
             AssertExtensions.Throws<ArgumentOutOfRangeException>("length", () => new Regex("pattern").Match("input", 0, 6));
         }
-
-        [Theory]
-        [InlineData(")")]
-        [InlineData("())")]
-        [InlineData("[a-z-[aeiuo]")]
-        [InlineData("[a-z-[aeiuo")]
-        [InlineData("[a-z-[b]")]
-        [InlineData("[a-z-[b")]
-        [InlineData("[b-a]")]
-        [InlineData(@"[a-c]{2,1}")]
-        [InlineData(@"\d{2147483648}")]
-        [InlineData("[a-z-[b][")]
-        [InlineData(@"\")]
-        [InlineData("(?()|||||)")]
-        public void Match_InvalidPattern(string pattern)
-        {
-            AssertExtensions.Throws<ArgumentException>(null, () => Regex.Match("input", pattern));
-            AssertExtensions.Throws<ArgumentException>(null, () => Regex.Match("input".AsMemory(), pattern));
-        }
-
+        
         [Fact]
         public void IsMatch_Invalid()
         {