Expand tests for array.new_data

Noticed that the existing tests didn't exercise out-of-bounds indexing of the
data segment, so I added a test for that. At the same time, since I was already
creating a dedicated `.wast` file for testing `array.new_data`, I also added a
few general tests to round the file out. Some of these might technically
duplicate things that already happen to be tested in `array.wast`, but I think
that's probably fine, and that it is good to have dedicated tests in this new
file. I can remove them if we'd rather not have these potential-duplicate tests.

Author: fitzgen

test/core/gc/array_new_data.wast

@@ -0,0 +1,50 @@
+(module
+  (type $arr (array (mut i8)))
+
+  (data $d "abcd")
+
+  (func (export "array-new-data") (param i32 i32) (result (ref $arr))
+    (array.new_data $arr $d (local.get 0) (local.get 1))
+  )
+)
+
+;; In-bounds data segment accesses.
+(assert_return (invoke "array-new-data" (i32.const 0) (i32.const 0)) (ref.array))
+(assert_return (invoke "array-new-data" (i32.const 0) (i32.const 4)) (ref.array))
+(assert_return (invoke "array-new-data" (i32.const 1) (i32.const 2)) (ref.array))
+(assert_return (invoke "array-new-data" (i32.const 4) (i32.const 0)) (ref.array))
+
+;; Out-of-bounds data segment accesses.
+(assert_trap (invoke "array-new-data" (i32.const 0) (i32.const 5)) "out of bounds memory access")
+(assert_trap (invoke "array-new-data" (i32.const 5) (i32.const 0)) "out of bounds memory access")
+
+(module
+  (type $arr (array (mut i8)))
+
+  (data $d "\aa\bb\cc\dd")
+
+  (func (export "array-new-data-contents") (result i32 i32)
+    (local (ref null $arr))
+    (local.set 0 (array.new_data $arr $d (i32.const 1) (i32.const 2)))
+    (array.get_u $arr (local.get 0) (i32.const 0))
+    (array.get_u $arr (local.get 0) (i32.const 1))
+  )
+)
+
+;; Array is initialized with the correct contents.
+(assert_return (invoke "array-new-data-contents") (i32.const 0xbb) (i32.const 0xcc))
+
+(module
+  (type $arr (array (mut i32)))
+
+  (data $d "\aa\bb\cc\dd")
+
+  (func (export "array-new-data-little-endian") (result i32)
+    (array.get $arr
+               (array.new_data $arr $d (i32.const 0) (i32.const 1))
+               (i32.const 0))
+  )
+)
+
+;; Data segments are interpreted as little-endian.
+(assert_return (invoke "array-new-data-little-endian") (i32.const 0xddccbbaa))