Change the type of padding input to array

fix #224

index.bs

@@ -1563,13 +1563,14 @@ dictionary MLPadOptions {
 };
 
 partial interface MLGraphBuilder {
-  MLOperand pad(MLOperand input, MLOperand padding, optional MLPadOptions options = {});
+  MLOperand pad(MLOperand input, sequence<sequence<long>> padding,
+                optional MLPadOptions options = {});
 };
 </script>
 <div algorithm=pad>
     **Arguments:**
         - *input*: an {{MLOperand}}. The input tensor.
-        - *padding*: an {{MLOperand}}. The 2-D Tensor of integer values indicating the number of padding values to add at the beginning and end of each input dimensions. The tensor has shape [*n*, 2] where *n* is the rank of the input tensor. For each dimension *D* of *input*, *padding[D, 0]* indicates how many values to add before the content in that dimension, and *padding[D, 1]* indicates how many values to add after the content in that dimension.
+        - *padding*: a sequence of length 2, where each element is a sequence of {{long}} whose length is equal to the rank of the input tensor. The integer values indicating the number of padding values to add at the beginning and end of each input dimensions. For each dimension *D* of *input*, *padding[D, 0]* indicates how many values to add before the content in that dimension, and *padding[D, 1]* indicates how many values to add after the content in that dimension.
         - *options*: an optional {{MLPadOptions}}. The optional parameters of the operation.
             - *mode*: a {{MLPaddingMode}}. The different ways to pad the tensor. When not set, it's assumed to be "constant".
             - *value*: a {{float}}. The pad value when the *options.mode* is set to *"constant"*. When not set, it's assumed to be 0.
@@ -1582,8 +1583,7 @@ partial interface MLGraphBuilder {
       { type: 'float32', dimensions: [2,3] }, new Float32Array([1,2,3,4,5,6]));
 
     // padding: [[1,1], [2,2]]
-    const padding = builder.constant(
-      { type: 'float32', dimensions: [2,2] }, new Float32Array([1,1,2,2]));
+    const padding = [[1,1], [2,2]];
 
     // "constant" padded:
     //    [[0,0,0,0,0,0,0],