Add a .wast test to exercise v128 and GC const expression evaluation (#13285)

Not all paths related to both GC and v128 were covered by our existing tests.

Author: fitzgen

tests/misc_testsuite/gc/const-expr-gc-simd.wast

@@ -0,0 +1,49 @@
+;;! gc = true
+;;! simd = true
+
+;; Tests for GC const-expression evaluation with SIMD types.
+
+;; Simple v128.const global
+(module
+  (global $g v128 (v128.const i32x4 1 2 3 4))
+
+  (func (export "v128-simple") (result v128)
+    (global.get $g)
+  )
+)
+(assert_return (invoke "v128-simple") (v128.const i32x4 1 2 3 4))
+
+;; struct.new_default with a v128 field
+(module
+  (type $s (struct (field v128)))
+
+  (global $g anyref (struct.new_default $s))
+
+  (func (export "v128-struct-default") (result v128)
+    (struct.get $s 0 (ref.cast (ref $s) (global.get $g)))
+  )
+)
+(assert_return (invoke "v128-struct-default") (v128.const i32x4 0 0 0 0))
+
+;; array.new_fixed with v128.const elements
+(module
+  (type $arr (array v128))
+
+  (global $g anyref (array.new_fixed $arr 2
+    (v128.const i32x4 1 2 3 4)
+    (v128.const i32x4 5 6 7 8)
+  ))
+
+  (func (export "v128-array-len") (result i32)
+    (array.len (ref.cast (ref $arr) (global.get $g)))
+  )
+  (func (export "v128-array-elem0") (result v128)
+    (array.get $arr (ref.cast (ref $arr) (global.get $g)) (i32.const 0))
+  )
+  (func (export "v128-array-elem1") (result v128)
+    (array.get $arr (ref.cast (ref $arr) (global.get $g)) (i32.const 1))
+  )
+)
+(assert_return (invoke "v128-array-len")   (i32.const 2))
+(assert_return (invoke "v128-array-elem0") (v128.const i32x4 1 2 3 4))
+(assert_return (invoke "v128-array-elem1") (v128.const i32x4 5 6 7 8))