[crankshaft] Fix deopt loop in String.fromCharCode on non-int32 inputs.

src/crankshaft/hydrogen.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/crankshaft/hydrogen.h"
 
 #include <sstream>
 
 #include "src/allocation-site-scopes.h"
 #include "src/ast/ast-numbering.h"
@@ skipping 8773 matching lines @@
         AddInstruction(char_code);
         HInstruction* result = NewUncasted<HStringCharFromCode>(char_code);
         ast_context()->ReturnInstruction(result, expr->id());
         return true;
       }
       break;
     case kStringFromCharCode:
       if (argument_count == 2) {
         HValue* argument = Pop();
         Drop(2);  // Receiver and function.
+        argument = AddUncasted<HForceRepresentation>(
+            argument, Representation::Integer32());
+        argument->SetFlag(HValue::kTruncatingToInt32);
         HInstruction* result = NewUncasted<HStringCharFromCode>(argument);
         ast_context()->ReturnInstruction(result, expr->id());
         return true;
       }
       break;
     case kMathExp:
       if (!FLAG_fast_math) break;
       // Fall through if FLAG_fast_math.
     case kMathRound:
     case kMathFround:
@@ skipping 4664 matching lines @@
     isolate()->GetHTracer()->TraceHydrogen(name(), graph_);
   }
 
 #ifdef DEBUG
   graph_->Verify(false);  // No full verify.
 #endif
 }
 
 }  // namespace internal
 }  // namespace v8