[wasm] Fix patching of table sizes.

BUG=chromium:752423
R=mtrofin@chromium.org,bradnelson@chromium.org

Change-Id: Ie6d80a82cd40b598e917a79842e6639e73be9194
Reviewed-on: https://chromium-review.googlesource.com/606587Reviewed-by: Mircea Trofin <mtrofin@chromium.org>
Commit-Queue: Ben Titzer <titzer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47251}

src/assembler.cc

@@ -341,11 +341,7 @@ void RelocInfo::update_wasm_function_table_size_reference(
     Isolate* isolate, uint32_t old_size, uint32_t new_size,
     ICacheFlushMode icache_flush_mode) {
   DCHECK(IsWasmFunctionTableSizeReference(rmode_));
-  uint32_t current_size_reference = wasm_function_table_size_reference();
-  uint32_t updated_size_reference =
-      new_size + (current_size_reference - old_size);
-  unchecked_update_wasm_size(isolate, updated_size_reference,
-                             icache_flush_mode);
+  unchecked_update_wasm_size(isolate, new_size, icache_flush_mode);
 }
 
 void RelocInfo::set_target_address(Isolate* isolate, Address target,

test/mjsunit/regress/wasm/regress-752423.js

+// Copyright 2017 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.
+
+// Flags: --expose-wasm
+
+'use strict';
+
+load("test/mjsunit/wasm/wasm-constants.js");
+load("test/mjsunit/wasm/wasm-module-builder.js");
+
+var builder = new WasmModuleBuilder();
+builder.addImportedTable("x", "table", 1, 10000000);
+builder.addFunction("main", kSig_i_i)
+  .addBody([
+    kExprI32Const, 0,
+    kExprGetLocal, 0,
+    kExprCallIndirect, 0, kTableZero])
+  .exportAs("main");
+let module = new WebAssembly.Module(builder.toBuffer());
+let table = new WebAssembly.Table({element: "anyfunc",
+  initial: 1, maximum:1000000});
+let instance = new WebAssembly.Instance(module, {x: {table:table}});
+
+table.grow(0x40001);
+
+let instance2 = new WebAssembly.Instance(module, {x: {table:table}});
+
+try {
+  instance2.exports.main(402982); // should be OOB
+} catch (e) {
+  print("Correctly caught: ", e);
+}