[vm] Revise Dart_IntegerToHexCString to avoid dependency on Bigint, v.2

[vm] Revise Dart_IntegerToHexCString to avoid dependency on Bigint, v.2

Reapply 3d4838fc70a5439437a5ceb4247551315c294477 with the following
modifications:
* define PRIX64 to fix compilation errors on Windows;
* add and use short form format specifiers PX and PX64 to make it
  uniform with other format specifiers.

Original review: https://codereview.chromium.org/2987183002

Description of the original CL:

Until this change, implementation of Dart_IntegerToHexCString()
always created Bigint objects and used Bigint::ToHexCString() to do
the work.

In --limit-ints-to-64-bits mode (with Dart integers limited to 64
bits) Bigints are banned and should not be used.
This CL revises Dart_IntegerToHexCString implementation to avoid
creating Bigint objects for Smi and Mint arguments, so it would
work in --limit-ints-to-64-bits mode.

Also, this CL adds test case to lock down the behavior of
Dart_IntegerToHexCString.

R=zra@google.com

Issue: https://github.com/dart-lang/sdk/issues/30103
Committed: https://github.com/dart-lang/sdk/commit/ed74405635da8dfa940bf872391ad29d3e89fe59

[alexmarkov, 2017-08-01 17:27:41]

alexmarkov@google.com changed reviewers:
+ asiva@google.com, zra@google.com

[zra, 2017-08-01 17:46:08]

lgtm

[alexmarkov, 2017-08-01 17:49:56]

Description was changed from

==========
[vm] Revise Dart_IntegerToHexCString to avoid dependency on Bigint, v.2

Reapply 3d4838fc70a5439437a5ceb4247551315c294477 with the following
modifications:
* define PRIX64 to fix compilation errors on Windows;
* add and use short form format specifiers PX and PX64 to make it
  uniform with other format specifiers.

Original review: https://codereview.chromium.org/2987183002

Description of the original CL:

Until this change, implementation of Dart_IntegerToHexCString()
always created Bigint objects and used Bigint::ToHexCString() to do
the work.

In --limit-ints-to-64-bits mode (with Dart integers limited to 64
bits) Bigints are banned and should not be used.
This CL revises Dart_IntegerToHexCString implementation to avoid
creating Bigint objects for Smi and Mint arguments, so it would
work in --limit-ints-to-64-bits mode.

Also, this CL adds test case to lock down the behavior of
Dart_IntegerToHexCString.

Issue: https://github.com/dart-lang/sdk/issues/30103
==========

to

==========
[vm] Revise Dart_IntegerToHexCString to avoid dependency on Bigint, v.2

Reapply 3d4838fc70a5439437a5ceb4247551315c294477 with the following
modifications:
* define PRIX64 to fix compilation errors on Windows;
* add and use short form format specifiers PX and PX64 to make it
  uniform with other format specifiers.

Original review: https://codereview.chromium.org/2987183002

Description of the original CL:

Until this change, implementation of Dart_IntegerToHexCString()
always created Bigint objects and used Bigint::ToHexCString() to do
the work.

In --limit-ints-to-64-bits mode (with Dart integers limited to 64
bits) Bigints are banned and should not be used.
This CL revises Dart_IntegerToHexCString implementation to avoid
creating Bigint objects for Smi and Mint arguments, so it would
work in --limit-ints-to-64-bits mode.

Also, this CL adds test case to lock down the behavior of
Dart_IntegerToHexCString.

R=zra@google.com

Issue: https://github.com/dart-lang/sdk/issues/30103
Committed:
https://github.com/dart-lang/sdk/commit/ed74405635da8dfa940bf872391ad29d3e89fe59
==========

[alexmarkov, 2017-08-01 17:49:57]

Committed patchset #1 (id:1) manually as
ed74405635da8dfa940bf872391ad29d3e89fe59 (presubmit successful).