Remove mail blockquote special case handling.

LayoutTests/editing/pasteboard/paste-blockquote-and-paragraph-break-expected.txt

Index: LayoutTests/editing/pasteboard/paste-blockquote-and-paragraph-break-expected.txt
diff --git a/LayoutTests/editing/pasteboard/paste-blockquote-and-paragraph-break-expected.txt b/LayoutTests/editing/pasteboard/paste-blockquote-and-paragraph-break-expected.txt
deleted file mode 100644
index 576fe53cb6295d0922ead92d83dc0ea46eaf6a83..0000000000000000000000000000000000000000
--- a/LayoutTests/editing/pasteboard/paste-blockquote-and-paragraph-break-expected.txt
+++ /dev/null
@@ -1,45 +0,0 @@
-We copy and paste a blockquoted paragraph plus a paragraph break.
-The paragraph break shouldn't be inside the blockquote on paste.  
-You should see 'hello' (blockquoted), 'world' (not quoted, black text), 'hello' (blockquoted), empty paragraph.
-See <rdar://problem/5368833<
-
-Before paste:
-| <br>
-| <blockquote>
-|   id="blockquote"
-|   type="cite"
-|   "hello"
-|   <br>
-| <br>
-
-After paste:
-| <blockquote>
-|   id="blockquote"
-|   type="cite"
-|   "hello"
-|   <br>
-| <div>
-|   <#selection-caret>
-|   <br>
-| <blockquote>
-|   id="blockquote"
-|   type="cite"
-|   "hello"
-|   <br>
-| <br>
-
-After inserting "world":
-| <blockquote>
-|   id="blockquote"
-|   type="cite"
-|   "hello"
-|   <br>
-| <div>
-|   "world<#selection-caret>"
-|   <br>
-| <blockquote>
-|   id="blockquote"
-|   type="cite"
-|   "hello"
-|   <br>
-| <br>