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/CodeGen/CGCall.cpp b/lib/CodeGen/CGCall.cpp
index b5195c4..97391bc 100644
--- a/lib/CodeGen/CGCall.cpp
+++ b/lib/CodeGen/CGCall.cpp
@@ -142,8 +142,8 @@
   assert(!RD->hasFlexibleArrayMember() && 
          "Cannot expand structure with flexible array.");
   
-  for (RecordDecl::field_iterator i = RD->field_begin(Context), 
-         e = RD->field_end(Context); i != e; ++i) {
+  for (RecordDecl::field_iterator i = RD->field_begin(), e = RD->field_end();
+         i != e; ++i) {
     const FieldDecl *FD = *i;
     assert(!FD->isBitField() && 
            "Cannot expand structure with bit-field members.");
@@ -167,8 +167,8 @@
   assert(LV.isSimple() && 
          "Unexpected non-simple lvalue during struct expansion.");  
   llvm::Value *Addr = LV.getAddress();
-  for (RecordDecl::field_iterator i = RD->field_begin(getContext()), 
-         e = RD->field_end(getContext()); i != e; ++i) {
+  for (RecordDecl::field_iterator i = RD->field_begin(), e = RD->field_end();
+         i != e; ++i) {
     FieldDecl *FD = *i;    
     QualType FT = FD->getType();
 
@@ -194,8 +194,8 @@
   RecordDecl *RD = RT->getDecl();
   assert(RV.isAggregate() && "Unexpected rvalue during struct expansion");
   llvm::Value *Addr = RV.getAggregateAddr();
-  for (RecordDecl::field_iterator i = RD->field_begin(getContext()), 
-         e = RD->field_end(getContext()); i != e; ++i) {
+  for (RecordDecl::field_iterator i = RD->field_begin(), e = RD->field_end();
+         i != e; ++i) {
     FieldDecl *FD = *i;    
     QualType FT = FD->getType();