Fixed Assumes class to be more debugger friendly.

Assumes.InternalErrorException.cs

@@ -27,6 +27,7 @@ namespace Microsoft
             /// <summary>
             /// Initializes a new instance of the <see cref="InternalErrorException"/> class.
             /// </summary>
+            [DebuggerStepThrough]
             public InternalErrorException(string message = null, bool showAssert = true)
                 : base(message ?? Strings.InternalExceptionMessage)
             {
@@ -36,6 +37,7 @@ namespace Microsoft
             /// <summary>
             /// Initializes a new instance of the <see cref="InternalErrorException"/> class.
             /// </summary>
+            [DebuggerStepThrough]
             public InternalErrorException(string message, Exception innerException, bool showAssert = true)
                 : base(message ?? Strings.InternalExceptionMessage, innerException)
             {
@@ -45,6 +47,7 @@ namespace Microsoft
             /// <summary>
             /// Initializes a new instance of the <see cref="InternalErrorException"/> class.
             /// </summary>
+            [DebuggerStepThrough]
             protected InternalErrorException(SerializationInfo info, StreamingContext context)
                 : base(info, context)
             {
@@ -58,6 +61,7 @@ namespace Microsoft
             /// The assertion dialog may yet be suppressed if 
             /// ((DefaultTraceListener)System.Diagnostics.Trace.Listeners["Default"]).AssertUiEnabled == false
             /// </remarks>
+            [DebuggerStepThrough]
             private void ShowAssertDialog(bool showAssert)
             {
                 if (showAssert)

Assumes.cs

@@ -190,13 +190,16 @@ namespace Microsoft
         /// Throws an public exception.
         /// </summary>
         /// <returns>Nothing, as this method always throws.  The signature allows for "throwing" Fail so C# knows execution will stop.</returns>
+        [DebuggerStepThrough]
         public static Exception Fail(string message = null, bool showAssert = true)
         {
-            // Keep these two as separate lines of code, so the debugger can come in during the assert dialog
-            // that the exception's constructor displays, and the debugger can then be made to skip the throw
-            // in order to continue the investigation.
             var exception = new InternalErrorException(message, showAssert);
-            throw exception;
+            bool continueToThrow = true; // allows debuggers to skip throwing.
+            if (continueToThrow) {
+                throw exception;
+            } else {
+                return null;
+            }
         }
 
         /// <summary>