Revert "Don't assert if materializing before seeing any function bodies"

This reverts r251667 since it broke the bots.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@251671 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Bitcode/Reader/BitcodeReader.cpp

@@ -3054,9 +3054,7 @@ std::error_code BitcodeReader::rememberAndSkipFunctionBodies() {
 
   if (Stream.AtEndOfStream()) return error("Could not find function in stream");
 
-  if (!SeenFirstFunctionBody)
-    return error("Trying to materialize functions before seeing function blocks");
-
+  assert(SeenFirstFunctionBody);
   // An old bitcode file with the symbol table at the end would have
   // finished the parse greedily.
   assert(SeenValueSymbolTable);