Stop printing double { characters on Dictionary StructuredData objects
when Dumping, thanks to Devin to catching the edit mistake I made in 
r276079.

llvm-svn: 276351
diff --git a/lldb/source/Core/StructuredData.cpp b/lldb/source/Core/StructuredData.cpp
index 000dacb..95bdeb5 100644
--- a/lldb/source/Core/StructuredData.cpp
+++ b/lldb/source/Core/StructuredData.cpp
@@ -291,7 +291,7 @@
     s << "{";
     if (pretty_print)
     {
-        s << "{\n";
+        s << "\n";
         s.IndentMore();
     }
     for (const auto &pair : m_dict)