[wasm] Implement polymorphic checking, matching the reference interpreter.

test/cctest/wasm/test-wasm-breakpoints.cc

 // Copyright 2016 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/debug/debug-interface.h"
 #include "src/frames-inl.h"
 #include "src/property-descriptor.h"
 #include "src/utils.h"
 #include "src/wasm/wasm-macro-gen.h"
 #include "src/wasm/wasm-objects.h"
@@ skipping 246 matching lines @@
 
   // return arg0
   BUILD(runner, WASM_RETURN1(WASM_GET_LOCAL(0)));
   // for (int i = 0; i < 10; ++i) { f2(i); }
   BUILD(f2, WASM_LOOP(
                 WASM_BR_IF(0, WASM_BINOP(kExprI32GeU, WASM_GET_LOCAL(0),
                                          WASM_I32V_1(10))),
                 WASM_SET_LOCAL(
                     0, WASM_BINOP(kExprI32Sub, WASM_GET_LOCAL(0), WASM_ONE)),
                 WASM_CALL_FUNCTION(runner.function_index(), WASM_GET_LOCAL(0)),
-                WASM_BR(1)));
+                WASM_DROP, WASM_BR(1)));
 
   Isolate* isolate = runner.main_isolate();
   Handle<JSFunction> main_fun_wrapper =
       runner.module().WrapCode(f2.function_index());
 
   // Set first breakpoint on the GetLocal (offset 19) before the Call.
   SetBreakpoint(runner, f2.function_index(), 19, 19);
 
   BreakHandler count_breaks(isolate,
                             {
                                 {19, BreakHandler::StepIn},   // GetLocal
                                 {21, BreakHandler::StepIn},   // Call
                                 {1, BreakHandler::StepOut},   // in f2
                                 {23, BreakHandler::Continue}  // After Call
                             });
 
   Handle<Object> global(isolate->context()->global_object(), isolate);
   CHECK(!Execution::Call(isolate, main_fun_wrapper, global, 0, nullptr)
              .is_null());
 }