Remove generation of asm.js SIMD imports SIMD_Int32x4_fromUint32x4 an…

…d SIMD_Uint32x4_fromInt32x4. These are currently not used, also see https://bugzilla.mozilla.org/show_bug.cgi?id=1313512.

emscripten.py

@@ -852,9 +852,13 @@ def add_simd_cast(dst, src):
         return '  var SIMD_' + dst + '_from' + src + '=SIMD_' + dst + '.from' + src + ';\n'
       def add_simd_casts(t1, t2):
         return add_simd_cast(t1, t2) + add_simd_cast(t2, t1)
-      if metadata['simdInt8x16'] and metadata['simdUint8x16']: asm_global_funcs += add_simd_casts('Int8x16', 'Uint8x16')
-      if metadata['simdInt16x8'] and metadata['simdUint16x8']: asm_global_funcs += add_simd_casts('Int16x8', 'Uint16x8')
-      if metadata['simdInt32x4'] and metadata['simdUint32x4']: asm_global_funcs += add_simd_casts('Int32x4', 'Uint32x4')
+
+      # Bug: Skip importing conversions for int<->uint for now, they don't validate as asm.js. https://bugzilla.mozilla.org/show_bug.cgi?id=1313512
+      # This is not an issue when building SSEx code, because it doesn't use these. (but it will be an issue if using SIMD.js intrinsics from vector.h to explicitly call these)
+#      if metadata['simdInt8x16'] and metadata['simdUint8x16']: asm_global_funcs += add_simd_casts('Int8x16', 'Uint8x16')
+#      if metadata['simdInt16x8'] and metadata['simdUint16x8']: asm_global_funcs += add_simd_casts('Int16x8', 'Uint16x8')
+#      if metadata['simdInt32x4'] and metadata['simdUint32x4']: asm_global_funcs += add_simd_casts('Int32x4', 'Uint32x4')
+
       if metadata['simdInt32x4'] and metadata['simdFloat32x4']: asm_global_funcs += add_simd_casts('Int32x4', 'Float32x4')
       if metadata['simdUint32x4'] and metadata['simdFloat32x4']: asm_global_funcs += add_simd_casts('Uint32x4', 'Float32x4')
       if metadata['simdInt32x4'] and metadata['simdFloat64x2']: asm_global_funcs += add_simd_cast('Int32x4', 'Float64x2') # Unofficial, needed for emscripten_int32x4_fromFloat64x2