Revert [BitcodeReader] Validate OpNum, before accessing Record array.

This reverts r365750 (git commit 8b222ecf27)

llvm-dis runs out of memory while opening invalid-fcmp-opnum.bc on
llvm-hexagon-elf, probably because the bitcode file contains other
suspicious values.

http://lab.llvm.org:8011/builders/llvm-hexagon-elf/builds/21949

llvm-svn: 365757

llvm/lib/Bitcode/Reader/BitcodeReader.cpp

@@ -4165,10 +4165,6 @@ Error BitcodeReader::parseFunctionBody(Function *F) {
           popValue(Record, OpNum, NextValueNo, LHS->getType(), RHS))
         return error("Invalid record");
 
-      if (OpNum >= Record.size())
-        return error(
-            "Invalid record: operand number exceeded available operands");
-
       unsigned PredVal = Record[OpNum];
       bool IsFP = LHS->getType()->isFPOrFPVectorTy();
       FastMathFlags FMF;