Revert "VenusCommandFilter/AbstractVsTextViewFilter uses incorrect buffer when providing values"

This reverts commit 3bc73cab.

src/VisualStudio/Core/Def/Implementation/AbstractVsTextViewFilter`2.cs

@@ -11,7 +11,6 @@
 using Microsoft.VisualStudio.Editor;
 using Microsoft.VisualStudio.LanguageServices.Implementation.LanguageService;
 using Microsoft.VisualStudio.LanguageServices.Implementation.ProjectSystem;
-using Microsoft.VisualStudio.Text;
 using Microsoft.VisualStudio.Text.Editor;
 using Microsoft.VisualStudio.TextManager.Interop;
 using Roslyn.Utilities;
@@ -48,24 +47,18 @@ int IVsTextViewFilter.GetDataTipText(TextSpan[] pSpan, out string pbstrText)
         }
 
         protected virtual int GetDataTipTextImpl(TextSpan[] pSpan, out string pbstrText)
-        {
-            var subjectBuffer = WpfTextView.GetBufferContainingCaret();
-            if (subjectBuffer == null)
-            {
-                pbstrText = null;
-                return VSConstants.E_FAIL;
-            }
-
-            return GetDataTipTextImpl(subjectBuffer, pSpan, out pbstrText);
-        }
- 
-        protected int GetDataTipTextImpl(ITextBuffer subjectBuffer, TextSpan[] pSpan, out string pbstrText)
         {
             pbstrText = null;
 
             var debugInfo = LanguageService.LanguageDebugInfo;
             if (debugInfo != null)
             {
+                var subjectBuffer = WpfTextView.GetBufferContainingCaret();
+                if (subjectBuffer == null)
+                {
+                    return VSConstants.E_FAIL;
+                }
+
                 var vsBuffer = EditorAdaptersFactory.GetBufferAdapter(subjectBuffer);
 
                 // TODO: broken in REPL

src/VisualStudio/Core/Def/Implementation/Venus/VenusCommandFilter.cs

@@ -83,7 +83,7 @@ protected override int GetDataTipTextImpl(TextSpan[] pSpan, out string pbstrText
                 // Next, we'll check to see if there is actually a DataTip for this candidate.
                 // If there is, we'll map this span back to the DataBuffer and return it.
                 pSpan[0] = candidateSpan.ToVsTextSpan();
-                int hr = base.GetDataTipTextImpl(_subjectBuffer, pSpan, out pbstrText);
+                int hr = base.GetDataTipTextImpl(pSpan, out pbstrText);
                 if (ErrorHandler.Succeeded(hr))
                 {
                     var subjectSpan = _subjectBuffer.CurrentSnapshot.GetSpan(pSpan[0]);