Prefer using Array.Length as upper for loop limit (#2513)

Port of dotnet/coreclr#8923

Author: mikedn

src/System.Private.CoreLib/src/System/Delegate.cs

@@ -630,7 +630,7 @@ public virtual Delegate[] GetInvocationList()
                 int invocationCount = (int)m_extraFunctionPointerOrData;
                 del = new Delegate[invocationCount];
 
-                for (int i = 0; i < invocationCount; i++)
+                for (int i = 0; i < del.Length; i++)
                     del[i] = invocationList[i];
             }
             return del;

src/System.Private.CoreLib/src/System/Reflection/Assembly.cs

@@ -38,19 +38,18 @@ public virtual Type[] GetTypes()
         {
             Module[] m = GetModules(false);
 
-            int numModules = m.Length;
             int finalLength = 0;
-            Type[][] moduleTypes = new Type[numModules][];
+            Type[][] moduleTypes = new Type[m.Length][];
 
-            for (int i = 0; i < numModules; i++)
+            for (int i = 0; i < moduleTypes.Length; i++)
             {
                 moduleTypes[i] = m[i].GetTypes();
                 finalLength += moduleTypes[i].Length;
             }
 
             int current = 0;
             Type[] ret = new Type[finalLength];
-            for (int i = 0; i < numModules; i++)
+            for (int i = 0; i < moduleTypes.Length; i++)
             {
                 int length = moduleTypes[i].Length;
                 Array.Copy(moduleTypes[i], 0, ret, current, length);

src/System.Private.CoreLib/src/System/Runtime/CompilerServices/ConditionalWeakTable.cs

@@ -528,7 +528,7 @@ internal Container Resize(int newSize)
                 // Reallocate both buckets and entries and rebuild the bucket and entries from scratch.
                 // This serves both to scrub entries with expired keys and to put the new entries in the proper bucket.
                 int[] newBuckets = new int[newSize];
-                for (int bucketIndex = 0; bucketIndex < newSize; bucketIndex++)
+                for (int bucketIndex = 0; bucketIndex < newBuckets.Length; bucketIndex++)
                 {
                     newBuckets[bucketIndex] = -1;
                 }