Fixing a conflict detection bug in tooling::deduplicate

If a Replacment is contained within the conflict range being built, the
conflict range would be erroneously shortened. Now fixed. Tests updated to
catch this case.

llvm-svn: 188287
diff --git a/clang/lib/Tooling/Refactoring.cpp b/clang/lib/Tooling/Refactoring.cpp
index 8599f97..52daaeb 100644
--- a/clang/lib/Tooling/Refactoring.cpp
+++ b/clang/lib/Tooling/Refactoring.cpp
@@ -206,8 +206,9 @@
     if (ConflictRange.overlapsWith(Current)) {
       // Extend conflicted range
       ConflictRange = Range(ConflictRange.getOffset(),
-                            Current.getOffset() + Current.getLength() -
-                                ConflictRange.getOffset());
+                            std::max(ConflictRange.getLength(),
+                                     Current.getOffset() + Current.getLength() -
+                                         ConflictRange.getOffset()));
       ++ConflictLength;
     } else {
       if (ConflictLength > 1)