[wasm] Fix location for error in asm.js ToNumber conversion

src/wasm/wasm-module-builder.cc

 // Copyright 2015 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/signature.h"
 
 #include "src/handles.h"
 #include "src/v8.h"
 #include "src/zone/zone-containers.h"
 
@@ skipping 132 matching lines @@
 void WasmFunctionBuilder::ExportAs(Vector<const char> name) {
   exported_names_.push_back(ZoneVector<char>(
       name.start(), name.start() + name.length(), builder_->zone()));
 }
 
 void WasmFunctionBuilder::SetName(Vector<const char> name) {
   name_.resize(name.length());
   memcpy(name_.data(), name.start(), name.length());
 }
 
-void WasmFunctionBuilder::AddAsmWasmOffset(int asm_position) {
+void WasmFunctionBuilder::AddAsmWasmOffset(int call_position,
+                                           int to_number_position) {
   // We only want to emit one mapping per byte offset:
   DCHECK(asm_offsets_.size() == 0 || body_.size() > last_asm_byte_offset_);
 
   DCHECK_LE(body_.size(), kMaxUInt32);
   uint32_t byte_offset = static_cast<uint32_t>(body_.size());
   asm_offsets_.write_u32v(byte_offset - last_asm_byte_offset_);
   last_asm_byte_offset_ = byte_offset;
 
-  DCHECK_GE(asm_position, 0);
-  asm_offsets_.write_i32v(asm_position - last_asm_source_position_);
-  last_asm_source_position_ = asm_position;
+  DCHECK_GE(call_position, 0);
+  asm_offsets_.write_i32v(call_position - last_asm_source_position_);
+
+  DCHECK_GE(to_number_position, 0);
+  asm_offsets_.write_i32v(to_number_position - call_position);
+  last_asm_source_position_ = to_number_position;
 }
 
 void WasmFunctionBuilder::WriteSignature(ZoneBuffer& buffer) const {
   buffer.write_u32v(signature_index_);
 }
 
 void WasmFunctionBuilder::WriteExports(ZoneBuffer& buffer) const {
   for (auto name : exported_names_) {
     buffer.write_size(name.size());
     buffer.write(reinterpret_cast<const byte*>(name.data()), name.size());
@@ skipping 356 matching lines @@
   // Emit the offset table per function.
   for (auto function : functions_) {
     function->WriteAsmWasmOffsetTable(buffer);
   }
   // Append a 0 to indicate that this is an encoded table.
   buffer.write_u8(0);
 }
 }  // namespace wasm
 }  // namespace internal
 }  // namespace v8