[sourcekitd] Make code-completion obey the semantic-editor-delay

These are semantic requests and should obey the delay to ensure we don't
trigger too many crashes.

rdar://18326221

Author: benlangmuir

tools/SourceKit/tools/sourcekitd/lib/API/Requests.cpp

@@ -720,6 +720,9 @@ handleSemanticRequest(RequestDict Req,
 
   llvm::SmallString<64> ErrBuf;
 
+  if (isSemanticEditorDisabled())
+      return Rec(createErrorRequestFailed("semantic editor is disabled"));
+
   if (ReqUID == RequestCodeComplete) {
     std::unique_ptr<llvm::MemoryBuffer>
     InputBuf = getInputBufForRequest(SourceFile, SourceText, ErrBuf);
@@ -767,9 +770,6 @@ handleSemanticRequest(RequestDict Req,
     return Rec(indexSource(*SourceFile, Args, Hash));
   }
 
-  if (isSemanticEditorDisabled())
-      return Rec(createErrorRequestFailed("semantic editor is disabled"));
-
   if (ReqUID == RequestCursorInfo) {
     LangSupport &Lang = getGlobalContext().getSwiftLangSupport();