[wasm] Implemented F32Trunc as a turbofan graph based on int32 instructions.

src/compiler/wasm-compiler.h

Index: src/compiler/wasm-compiler.h
diff --git a/src/compiler/wasm-compiler.h b/src/compiler/wasm-compiler.h
index 1a17a832e4e94c18c22b774aea283a698114d473..f0c54352f87b7574a7b93f813baa8cfe59ec00b2 100644
--- a/src/compiler/wasm-compiler.h
+++ b/src/compiler/wasm-compiler.h
@@ -176,6 +176,7 @@ class WasmGraphBuilder {
   Node* BuildI32Popcnt(Node* input);
   Node* BuildI64Ctz(Node* input);
   Node* BuildI64Popcnt(Node* input);
+  Node* BuildF32Trunc(Node* input);
 
   Node** Realloc(Node** buffer, size_t count) {
     Node** buf = Buffer(count);