De-ASTContext-ify DeclContext.

Remove ASTContext parameter from DeclContext's methods. This change cascaded down to other Decl's methods and changes to call sites started "escalating".
Timings using pre-tokenized "cocoa.h" showed only a ~1% increase in time run between and after this commit.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@74506 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/AST/DeclPrinter.cpp b/lib/AST/DeclPrinter.cpp
index b46656a..ca25ed2 100644
--- a/lib/AST/DeclPrinter.cpp
+++ b/lib/AST/DeclPrinter.cpp
@@ -171,8 +171,7 @@
     Indentation += Policy.Indentation;
 
   llvm::SmallVector<Decl*, 2> Decls;
-  for (DeclContext::decl_iterator D = DC->decls_begin(Context),
-         DEnd = DC->decls_end(Context);
+  for (DeclContext::decl_iterator D = DC->decls_begin(), DEnd = DC->decls_end();
        D != DEnd; ++D) {
     if (!Policy.Dump) {
       // Skip over implicit declarations in pretty-printing mode.
@@ -501,7 +500,7 @@
     VisitDeclContext(D);
     Indent() << "}";
   } else
-    Visit(*D->decls_begin(Context));
+    Visit(*D->decls_begin());
 }
 
 void DeclPrinter::VisitTemplateDecl(TemplateDecl *D) {