[runtime] Specifically handle robust RUNTIME_ASSERTs.

src/runtime/runtime-strings.cc

 // Copyright 2014 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/runtime/runtime-utils.h"
 
 #include "src/arguments.h"
 #include "src/regexp/jsregexp-inl.h"
 #include "src/string-builder.h"
 #include "src/string-search.h"
@@ skipping 280 matching lines @@
     CONVERT_SMI_ARG_CHECKED(from_number, 1);
     CONVERT_SMI_ARG_CHECKED(to_number, 2);
     start = from_number;
     end = to_number;
   } else {
     CONVERT_DOUBLE_ARG_CHECKED(from_number, 1);
     CONVERT_DOUBLE_ARG_CHECKED(to_number, 2);
     start = FastD2IChecked(from_number);
     end = FastD2IChecked(to_number);
   }
-  RUNTIME_ASSERT(end >= start);
-  RUNTIME_ASSERT(start >= 0);
-  RUNTIME_ASSERT(end <= string->length());
+  // The following condition is intentionally robust because the SubStringStub
+  // delegates here and we test this in cctest/test-strings/RobustSubStringStub.
+  if (end < start || start < 0 || end > string->length()) {
+    return isolate->ThrowIllegalOperation();
+  }
   isolate->counters()->sub_string_runtime()->Increment();
 
   return *isolate->factory()->NewSubString(string, start, end);
 }
 
 
 RUNTIME_FUNCTION(Runtime_StringAdd) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 2);
   CONVERT_ARG_HANDLE_CHECKED(String, str1, 0);
@@ skipping 892 matching lines @@
   SealHandleScope shs(isolate);
   DCHECK(args.length() == 2);
   if (!args[0]->IsString()) return isolate->heap()->undefined_value();
   if (!args[1]->IsNumber()) return isolate->heap()->undefined_value();
   if (std::isinf(args.number_at(1))) return isolate->heap()->nan_value();
   return __RT_impl_Runtime_StringCharCodeAtRT(args, isolate);
 }
 
 }  // namespace internal
 }  // namespace v8