[wasm] Remove redundant calls to {EndControl}.

The templatized function body decoder already properly terminates
control flow, it is not needed for the graph building implementation to
do that explicitly upon {Throw} and {Rethrow}.

R=titzer@chromium.org
BUG=v8:8091

Change-Id: I47a93135c41b4cdf2fa6b8f5c7abfd6c212aaa12
Reviewed-on: https://chromium-review.googlesource.com/c/1273239
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Ben Titzer <titzer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56559}

src/wasm/baseline/liftoff-compiler.cc

@@ -1816,7 +1816,7 @@ class LiftoffCompiler {
     unsupported(decoder, "simd");
   }
   void Throw(FullDecoder* decoder, const ExceptionIndexImmediate<validate>&,
-             Control* block, const Vector<Value>& args) {
+             const Vector<Value>& args) {
     unsupported(decoder, "throw");
   }
   void Rethrow(FullDecoder* decoder, Control* block) {

src/wasm/function-body-decoder-impl.h

@@ -660,7 +660,7 @@ struct ControlWithNamedConstructors : public ControlBase<Value> {
     const Value& input, Value* result)                                        \
   F(Simd8x16ShuffleOp, const Simd8x16ShuffleImmediate<validate>& imm,         \
     const Value& input0, const Value& input1, Value* result)                  \
-  F(Throw, const ExceptionIndexImmediate<validate>& imm, Control* block,      \
+  F(Throw, const ExceptionIndexImmediate<validate>& imm,                      \
     const Vector<Value>& args)                                                \
   F(Rethrow, Control* block)                                                  \
   F(CatchException, const ExceptionIndexImmediate<validate>& imm,             \
@@ -1482,8 +1482,7 @@ class WasmFullDecoder : public WasmDecoder<validate> {
             len = 1 + imm.length;
             if (!this->Validate(this->pc_, imm)) break;
             PopArgs(imm.exception->ToFunctionSig());
-            CALL_INTERFACE_IF_REACHABLE(Throw, imm, &control_.back(),
-                                        vec2vec(args_));
+            CALL_INTERFACE_IF_REACHABLE(Throw, imm, vec2vec(args_));
             EndControl();
             break;
           }

src/wasm/function-body-decoder.cc

@@ -408,7 +408,7 @@ class WasmGraphBuildingInterface {
   }
 
   void Throw(FullDecoder* decoder, const ExceptionIndexImmediate<validate>& imm,
-             Control* block, const Vector<Value>& value_args) {
+             const Vector<Value>& value_args) {
     int count = value_args.length();
     ZoneVector<TFNode*> args(count, decoder->zone());
     for (int i = 0; i < count; ++i) {
@@ -416,14 +416,12 @@ class WasmGraphBuildingInterface {
     }
     BUILD(Throw, imm.index, imm.exception, vec2vec(args));
     Unreachable(decoder);
-    EndControl(decoder, block);
   }
 
   void Rethrow(FullDecoder* decoder, Control* block) {
     TFNode* exception = block->try_info->exception;
     BUILD(Rethrow, exception);
     Unreachable(decoder);
-    EndControl(decoder, block);
   }
 
   void CatchException(FullDecoder* decoder,