[WebAssembly] Match llvm change to custom section size

[sbc100]

Summary

The content of custome sections no longer includes the
name itself.

See: https://reviews.llvm.org/D45579

[yurydelendik]

LGTM

lld/trunk/test/wasm/custom-sections.ll

entry:
   ret i32 0
 }
 
 !0 = !{ !"red", !"extra" }
 !wasm.custom_sections = !{ !0 }
 
 ; CHECK:        - Type:            CUSTOM
 ; CHECK-NEXT:     Name:            green
-; CHECK-NEXT:     Payload:         '05677265656E626172717578'
+; CHECK-NEXT:     Payload:         '626172717578'
 ; CHECK-NEXT:   - Type:            CUSTOM
 ; CHECK-NEXT:     Name:            red
-; CHECK-NEXT:     Payload:         037265646578747261666F6F
+; CHECK-NEXT:     Payload:         6578747261666F6F

lld/trunk/wasm/InputChunks.h

protected:
 
   StringRef Name;
   ArrayRef<uint8_t> Body;
 };
 
 // Represents a single Wasm Section within an input file.
 class InputSection : public InputChunk {
 public:
-  InputSection(const WasmSection &S, ObjFile *F);
+  InputSection(const WasmSection &S, ObjFile *F)
+      : InputChunk(F, InputChunk::Section), Section(S) {
+    assert(Section.Type == llvm::wasm::WASM_SEC_CUSTOM);
+  }
 
   StringRef getName() const override { return Section.Name; }
   uint32_t getComdat() const override { return UINT32_MAX; }
 
 protected:
-  ArrayRef<uint8_t> data() const override { return Payload; }
+  ArrayRef<uint8_t> data() const override { return Section.Content; }
 
   // Offset within the input section.  This is only zero since this chunk
   // type represents an entire input section, not part of one.
   uint32_t getInputSectionOffset() const override { return 0; }
 
   const WasmSection &Section;
-  ArrayRef<uint8_t> Payload;
 };
 
 } // namespace wasm
 
 std::string toString(const wasm::InputChunk *);
 } // namespace lld
 
 #endif // LLD_WASM_INPUT_CHUNKS_H

lld/trunk/wasm/InputChunks.cpp

 }
 
 void InputFunction::setTableIndex(uint32_t Index) {
   DEBUG(dbgs() << "InputFunction::setTableIndex: " << getName() << " -> "
                << Index << "\n");
   assert(!hasTableIndex());
   TableIndex = Index;
 }
-
-InputSection::InputSection(const WasmSection &S, ObjFile *F)
-    : InputChunk(F, InputChunk::Section), Section(S) {
-  assert(Section.Type == llvm::wasm::WASM_SEC_CUSTOM);
-  // TODO check LEB errors
-  unsigned Count;
-  uint64_t NameSize = llvm::decodeULEB128(Section.Content.data(), &Count);
-  uint32_t PayloadOffset = Count + NameSize;
-  Payload = Section.Content.slice(PayloadOffset);
-}