Revert "[wasm] Check the size of a function body before storing it"

This reverts commit 6c8aed76.

Reason for revert: Breaks some debug bots:
https://build.chromium.org/p/client.v8/builders/V8%20Linux64%20-%20debug/builds/16754
https://build.chromium.org/p/client.v8/builders/V8%20Win64%20-%20debug/builds/17654

Original change's description:
> [wasm] Check the size of a function body before storing it
> 
> We stored the size of a function body before we check that
> these values are valid. This caused a failing DCHECK in the constructor
> of WireBytesRef which checked for integer overflows. With this CL we
> check the size of the function body before we create the WireBytesRef.
> 
> R=​clemensh@chromium.org
> 
> Bug: chromium:738097
> Change-Id: I18f8b628c1499aae9c8e9340ea73c87f19e6f1d7
> Reviewed-on: https://chromium-review.googlesource.com/561000
> Commit-Queue: Andreas Haas <ahaas@chromium.org>
> Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#46442}

TBR=ahaas@chromium.org,clemensh@chromium.org

Change-Id: Ifd533c0dee369c746bc97fea13275ebc09ed5eff
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: chromium:738097
Reviewed-on: https://chromium-review.googlesource.com/561517Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#46445}

src/wasm/module-decoder.cc

@@ -665,15 +665,13 @@ class ModuleDecoder : public Decoder {
       errorf(pos, "function body count %u mismatch (%u expected)",
              functions_count, module_->num_declared_functions);
     }
-    for (uint32_t i = 0; i < functions_count; ++i) {
+    for (uint32_t i = 0; ok() && i < functions_count; ++i) {
       WasmFunction* function =
           &module_->functions[i + module_->num_imported_functions];
       uint32_t size = consume_u32v("body size");
-      uint32_t offset = pc_offset();
+      function->code = {pc_offset(), size};
       consume_bytes(size, "function body");
-      if (failed()) break;
-      function->code = {offset, size};
-      if (verify_functions) {
+      if (ok() && verify_functions) {
         ModuleBytesEnv module_env(module_.get(), nullptr,
                                   ModuleWireBytes(start_, end_));
         VerifyFunctionBody(module_->signature_zone->allocator(),

test/unittests/wasm/module-decoder-unittest.cc

@@ -1347,19 +1347,6 @@ TEST_F(WasmModuleVerifyTest, Regression_648070) {
   EXPECT_FAILURE(data);
 }
 
-TEST_F(WasmModuleVerifyTest, Regression_738097) {
-  // The function body size caused an integer overflow in the module decoder.
-  static const byte data[] = {
-      SIGNATURES_SECTION(1, SIG_ENTRY_v_v),  // --
-      FUNCTION_SIGNATURES_SECTION(1, 0),     // --
-      SECTION(Code, 1 + 5 + 1),              // --
-      1,                                     // --
-      U32V_5(0xffffffff),                    // function size,
-      0                                      // No real body
-  };
-  EXPECT_FAILURE(data);
-}
-
 TEST_F(WasmModuleVerifyTest, FunctionBodies_empty) {
   static const byte data[] = {
       EMPTY_SIGNATURES_SECTION,           // --