Use "this." in a few places to match the style of the project

src/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableDictionary`2+Builder.cs

@@ -345,7 +345,7 @@ namespace System.Collections.Immutable
                 Requires.Range(arrayIndex >= 0, "arrayIndex");
                 Requires.Range(array.Length >= arrayIndex + this.Count, "arrayIndex");
 
-                if (count == 0) 
+                if (this.count == 0) 
                 {
                     return;
                 }

src/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableDictionary`2.cs

@@ -780,7 +780,7 @@ namespace System.Collections.Immutable
             Requires.Range(arrayIndex >= 0, "arrayIndex");
             Requires.Range(array.Length >= arrayIndex + this.Count, "arrayIndex");
 
-            if (count == 0) 
+            if (this.count == 0) 
             {
                 return;
             }

src/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableHashSet`1.cs

@@ -562,7 +562,7 @@ namespace System.Collections.Immutable
             Requires.Range(arrayIndex >= 0, "arrayIndex");
             Requires.Range(array.Length >= arrayIndex + this.Count, "arrayIndex");
 
-            if (count == 0)
+            if (this.count == 0)
             {
                 return;
             }

src/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableList`1.cs

@@ -2590,7 +2590,7 @@ namespace System.Collections.Immutable
                 Requires.Range(arrayIndex >= 0, "arrayIndex");
                 Requires.Range(array.Length >= arrayIndex + this.Count, "arrayIndex");
 
-                if (count == 0)
+                if (this.count == 0)
                 {
                     return;
                 }

src/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableSortedDictionary`2.cs

@@ -1381,7 +1381,7 @@ namespace System.Collections.Immutable
                 Requires.Range(arrayIndex >= 0, "arrayIndex");
                 Requires.Range(array.Length >= arrayIndex + dictionarySize, "arrayIndex");
 
-                if (IsEmpty)
+                if (this.IsEmpty)
                 {
                     return;
                 }

src/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableSortedSet`1.cs

@@ -1689,7 +1689,7 @@ namespace System.Collections.Immutable
                 Requires.Range(arrayIndex >= 0, "arrayIndex");
                 Requires.Range(array.Length >= arrayIndex + this.Count, "arrayIndex");
 
-                if (IsEmpty)
+                if (this.IsEmpty)
                 {
                     return;
                 }

src/System.Collections.Immutable/src/System/Collections/Immutable/KeysOrValuesCollectionAccessor.cs

@@ -139,7 +139,7 @@ namespace System.Collections.Immutable
             Requires.Range(arrayIndex >= 0, "arrayIndex");
             Requires.Range(array.Length >= arrayIndex + this.Count, "arrayIndex");
 
-            if (Count == 0)
+            if (this.Count == 0)
             {
                 return;
             }