[lldb][NFC] Simplify ClangASTContext::GetBasicTypes

static convenience methods that do the clang::ASTContext -> ClangASTContext
conversion and handle errors by simply ignoring them are not a good idea.
diff --git a/lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionDeclMap.cpp b/lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionDeclMap.cpp
index bbc0312..f8e448ff 100644
--- a/lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionDeclMap.cpp
+++ b/lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionDeclMap.cpp
@@ -1724,17 +1724,15 @@
   if (target == nullptr)
     return;
 
-  ASTContext *scratch_ast_context =
-      target->GetScratchClangASTContext()->getASTContext();
+  ClangASTContext *scratch_ast_context = target->GetScratchClangASTContext();
 
-  TypeFromUser user_type(
-      ClangASTContext::GetBasicType(scratch_ast_context, eBasicTypeVoid)
-          .GetPointerType()
-          .GetLValueReferenceType());
-  TypeFromParser parser_type(
-      ClangASTContext::GetBasicType(m_ast_context, eBasicTypeVoid)
-          .GetPointerType()
-          .GetLValueReferenceType());
+  TypeFromUser user_type(scratch_ast_context->GetBasicType(eBasicTypeVoid)
+                             .GetPointerType()
+                             .GetLValueReferenceType());
+  ClangASTContext *own_context = ClangASTContext::GetASTContext(m_ast_context);
+  TypeFromParser parser_type(own_context->GetBasicType(eBasicTypeVoid)
+                                 .GetPointerType()
+                                 .GetLValueReferenceType());
   NamedDecl *var_decl = context.AddVarDecl(parser_type);
 
   std::string decl_name(context.m_decl_name.getAsString());
@@ -2024,8 +2022,9 @@
 
   if (copied_clang_type.IsAggregateType() &&
       copied_clang_type.GetCompleteType()) {
-    CompilerType void_clang_type =
-        ClangASTContext::GetBasicType(m_ast_context, eBasicTypeVoid);
+    ClangASTContext *own_context =
+        ClangASTContext::GetASTContext(m_ast_context);
+    CompilerType void_clang_type = own_context->GetBasicType(eBasicTypeVoid);
     CompilerType void_ptr_clang_type = void_clang_type.GetPointerType();
 
     CompilerType method_type = ClangASTContext::CreateFunctionType(
diff --git a/lldb/source/Symbol/ClangASTContext.cpp b/lldb/source/Symbol/ClangASTContext.cpp
index fbf5bd4..bee72b2 100644
--- a/lldb/source/Symbol/ClangASTContext.cpp
+++ b/lldb/source/Symbol/ClangASTContext.cpp
@@ -987,13 +987,9 @@
   return eBasicTypeInvalid;
 }
 
-CompilerType ClangASTContext::GetBasicType(ASTContext *ast,
-                                           ConstString name) {
-  if (ast) {
-    lldb::BasicType basic_type = ClangASTContext::GetBasicTypeEnumeration(name);
-    return ClangASTContext::GetBasicType(ast, basic_type);
-  }
-  return CompilerType();
+CompilerType ClangASTContext::GetBasicType(ConstString name) {
+  lldb::BasicType basic_type = ClangASTContext::GetBasicTypeEnumeration(name);
+  return GetBasicType(basic_type);
 }
 
 uint32_t ClangASTContext::GetPointerByteSize() {
@@ -1006,13 +1002,8 @@
 }
 
 CompilerType ClangASTContext::GetBasicType(lldb::BasicType basic_type) {
-  return GetBasicType(getASTContext(), basic_type);
-}
+  clang::ASTContext *ast = getASTContext();
 
-CompilerType ClangASTContext::GetBasicType(ASTContext *ast,
-                                           lldb::BasicType basic_type) {
-  if (!ast)
-    return CompilerType();
   lldb::opaque_compiler_type_t clang_type =
       GetOpaqueCompilerType(ast, basic_type);
 
@@ -4907,7 +4898,7 @@
 // Create related types using the current type's AST
 
 CompilerType ClangASTContext::GetBasicTypeFromAST(lldb::BasicType basic_type) {
-  return ClangASTContext::GetBasicType(getASTContext(), basic_type);
+  return ClangASTContext::GetBasicType(basic_type);
 }
 // Exploring the type