Add integers_double_overflow for JS

Demonstrates kaitai-io/kaitai_struct_javascript_runtime#16

Author: generalmimon

formats/integers_double_overflow.ksy

@@ -0,0 +1,34 @@
+# Tests reading un/signed 64-bit integers in languages representing integers as 64-bit floats ("double"s)
+# It is intended especially for JavaScript.
+meta:
+  id: integers_double_overflow
+seq:
+  - id: signed_safe_min_be # 0x00
+    type: s8be
+  - id: signed_safe_min_le # 0x08
+    type: s8le
+  - id: signed_safe_max_be # 0x10
+    type: s8be
+  - id: signed_safe_max_le # 0x18
+    type: s8le
+  - id: signed_unsafe_neg_be # 0x20
+    type: s8be
+  - id: signed_unsafe_neg_le # 0x28
+    type: s8le
+  - id: signed_unsafe_pos_be # 0x30
+    type: s8be
+  - id: signed_unsafe_pos_le # 0x38
+    type: s8le
+instances:
+  unsigned_safe_max_be:
+    pos: 0x10
+    type: u8be
+  unsigned_safe_max_le:
+    pos: 0x18
+    type: u8le
+  unsigned_unsafe_pos_be:
+    pos: 0x30
+    type: u8be
+  unsigned_unsafe_pos_le:
+    pos: 0x38
+    type: u8le

spec/ks/integers_double_overflow.kst

@@ -0,0 +1,19 @@
+id: integers_double_overflow
+data: integers_double_overflow.bin
+asserts:
+  - actual: signed_safe_min_be
+    expected: -9007199254740991
+  - actual: signed_safe_min_le
+    expected: -9007199254740991
+  - actual: signed_safe_max_be
+    expected: 9007199254740991
+  - actual: signed_safe_max_le
+    expected: 9007199254740991
+  - actual: signed_unsafe_neg_be.to_s
+    expected: '"-9007199254740993"'
+  - actual: signed_unsafe_neg_le.to_s
+    expected: '"-9007199254740993"'
+  - actual: signed_unsafe_pos_be.to_s
+    expected: '"9007199254740993"'
+  - actual: signed_unsafe_pos_be.to_s
+    expected: '"9007199254740993"'