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/Sema/SemaTemplateInstantiate.cpp b/lib/Sema/SemaTemplateInstantiate.cpp
index 8af9ca1..ff01e41 100644
--- a/lib/Sema/SemaTemplateInstantiate.cpp
+++ b/lib/Sema/SemaTemplateInstantiate.cpp
@@ -859,8 +859,8 @@
     Invalid = true;
 
   llvm::SmallVector<DeclPtrTy, 4> Fields;
-  for (RecordDecl::decl_iterator Member = Pattern->decls_begin(Context),
-         MemberEnd = Pattern->decls_end(Context); 
+  for (RecordDecl::decl_iterator Member = Pattern->decls_begin(),
+         MemberEnd = Pattern->decls_end(); 
        Member != MemberEnd; ++Member) {
     Decl *NewMember = InstantiateDecl(*Member, Instantiation, TemplateArgs);
     if (NewMember) {
@@ -996,8 +996,8 @@
 Sema::InstantiateClassMembers(SourceLocation PointOfInstantiation,
                               CXXRecordDecl *Instantiation,
                               const TemplateArgumentList &TemplateArgs) {
-  for (DeclContext::decl_iterator D = Instantiation->decls_begin(Context),
-                               DEnd = Instantiation->decls_end(Context);
+  for (DeclContext::decl_iterator D = Instantiation->decls_begin(),
+                               DEnd = Instantiation->decls_end();
        D != DEnd; ++D) {
     if (FunctionDecl *Function = dyn_cast<FunctionDecl>(*D)) {
       if (!Function->getBody())