[WebNN] Allow ops to handle ignoring an empty tensor as input (microsoft#22972)

### Description
Some ops should allow empty tensor as input, e.g. roi, scales inputs in
Resize
### Motivation and Context
It avoid some unexpected fallback for optional input with empty tensor.
e.g. roi and scales are both optional inputs in Resize, in some models
they have non-empty name but with empty initializer presented as `[0]`,
WebNN currently will fallback all nodes with 0 dimension, which is not
expected.

![image](https://github.com/user-attachments/assets/599ba351-b5f6-49ac-8a1f-69fb28dbaf9b)

Author: Honry

onnxruntime/core/providers/webnn/builders/helper.cc

@@ -69,7 +69,8 @@ bool IsNodeSupported(const Node& node, const GraphViewer& graph_viewer, const We
   }
 }
 
-bool IsTensorShapeSupported(const NodeArg& node_arg, const std::string& parent_name, const logging::Logger& logger) {
+bool IsTensorShapeSupported(const NodeArg& node_arg, const std::string& parent_name,
+                            const logging::Logger& logger, bool allow_empty_input) {
   const auto& node_arg_name = node_arg.Name();
   const auto* shape_proto = node_arg.Shape();
   // Optional tensors can be indicated by an empty name, just ignore it.
@@ -89,7 +90,7 @@ bool IsTensorShapeSupported(const NodeArg& node_arg, const std::string& parent_n
                             << "use sessionOptions.FreeDimensionOverrides to set a fixed shape: " << node_arg_name;
       return false;
     }
-    if (dim.dim_value() == 0) {
+    if (dim.dim_value() == 0 && !allow_empty_input) {
       LOGS(logger, VERBOSE) << "The shape of [" << node_arg_name << "] has 0 dimension which is not supported by WebNN";
       return false;
     }

onnxruntime/core/providers/webnn/builders/helper.h

@@ -181,7 +181,8 @@ inline bool IsEmptyTensor(const InitializedTensorSet& initializers, const std::s
   return std::any_of(dims.begin(), dims.end(), [](auto d) { return d == 0; });
 }
 
-bool IsTensorShapeSupported(const NodeArg& node_arg, const std::string& parent_name, const logging::Logger& logger);
+bool IsTensorShapeSupported(const NodeArg& node_arg, const std::string& parent_name,
+                            const logging::Logger& logger, bool allow_empty_input = false);
 
 // Get a list of groups of supported nodes, each group represents a subgraph supported by WebNN EP.
 std::vector<std::vector<NodeIndex>> GetSupportedNodes(const GraphViewer& graph_viewer,

onnxruntime/core/providers/webnn/builders/impl/base_op_builder.cc

@@ -45,7 +45,7 @@ bool BaseOpBuilder::HasSupportedInputs(const Node& node, const emscripten::val&
                                        const logging::Logger& logger) const {
   const auto node_name = MakeString("Node [", node.Name(), "] type [", node.OpType(), "]");
   for (const auto* input : node.InputDefs()) {
-    if (!IsTensorShapeSupported(*input, node_name, logger)) {
+    if (!IsTensorShapeSupported(*input, node_name, logger, allow_empty_tensor_as_input_)) {
       return false;
     }
   }

onnxruntime/core/providers/webnn/builders/impl/base_op_builder.h

@@ -22,6 +22,9 @@ class BaseOpBuilder : public IOpBuilder {
                            const logging::Logger& logger) const override final ORT_MUST_USE_RESULT;
 
  protected:
+  explicit BaseOpBuilder(bool allow_empty_tensor_as_input = false)
+      : allow_empty_tensor_as_input_(allow_empty_tensor_as_input) {
+  }
   virtual Status AddToModelBuilderImpl(ModelBuilder& model_builder, const Node& node,
                                        const logging::Logger& logger) const ORT_MUST_USE_RESULT = 0;
 
@@ -55,6 +58,8 @@ class BaseOpBuilder : public IOpBuilder {
   bool HasSupportedOpSet(const Node& node, const logging::Logger& logger) const;
   bool HasSupportedInputs(const Node& node, const emscripten::val& wnn_limits, const logging::Logger& logger) const;
   bool HasSupportedOutputs(const Node& node, const emscripten::val& wnn_limits, const logging::Logger& logger) const;
+
+  const bool allow_empty_tensor_as_input_;  // Some operators can handle ignoring an empty tensor as input.
 };
 
 }  // namespace webnn

onnxruntime/core/providers/webnn/builders/impl/resize_op_builder.cc

@@ -21,6 +21,8 @@ namespace webnn {
 class ResizeOpBuilder : public BaseOpBuilder {
   // Add operator related.
  public:
+  // Allow roi and scales potentially being empty inputs that are ignored during processing.
+  ResizeOpBuilder() : BaseOpBuilder(/*allow empty inputs*/ true) {}
   void AddInitializersToSkip(ModelBuilder& model_builder, const Node& node) const override;
 
  private: