[Intl] Change the behavior of percent format under "unit"

1. Sync with
https://github.com/tc39/proposal-unified-intl-numberformat/pull/57
so the formatting of {style: "unit" unit: "percent"} and
the formatting of {style: "percent:"} are treated different that
simplified the algorithm.
2. Store style into bit flags because we need it quickly during format.
3. Add more unit tests and regression test.

Bug: v8:9498
Change-Id: I75ed22fef1feb73ebf624bda70ebe45b80e7bc8b
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1704948Reviewed-by: Adam Klein <adamk@chromium.org>
Commit-Queue: Frank Tang <ftang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62834}

src/objects/js-number-format-inl.h

@@ -66,6 +66,17 @@ inline void JSNumberFormat::set_maximum_fraction_digits(int digits) {
   set_flags(hints);
 }
 
+inline void JSNumberFormat::set_style(Style style) {
+  DCHECK_GE(StyleBits::kMax, style);
+  int hints = flags();
+  hints = StyleBits::update(hints, style);
+  set_flags(hints);
+}
+
+inline JSNumberFormat::Style JSNumberFormat::style() const {
+  return StyleBits::decode(flags());
+}
+
 CAST_ACCESSOR(JSNumberFormat)
 
 }  // namespace internal

src/objects/js-number-format.h

@@ -92,6 +92,14 @@ class JSNumberFormat : public JSObject {
   inline int maximum_fraction_digits() const;
   inline void set_maximum_fraction_digits(int digits);
 
+  // [[Style]] is one of the values "decimal", "percent", "currency",
+  // or "unit" identifying the style of the number format.
+  // Note: "unit" is added in proposal-unified-intl-numberformat
+  enum class Style { DECIMAL, PERCENT, CURRENCY, UNIT };
+
+  inline void set_style(Style style);
+  inline Style style() const;
+
   // Layout description.
   DEFINE_FIELD_OFFSET_CONSTANTS(JSObject::kHeaderSize,
                                 TORQUE_GENERATED_JSNUMBER_FORMAT_FIELDS)
@@ -99,13 +107,18 @@ class JSNumberFormat : public JSObject {
 // Bit positions in |flags|.
 #define FLAGS_BIT_FIELDS(V, _)            \
   V(MinimumFractionDigitsBits, int, 5, _) \
-  V(MaximumFractionDigitsBits, int, 5, _)
+  V(MaximumFractionDigitsBits, int, 5, _) \
+  V(StyleBits, Style, 2, _)
 
   DEFINE_BIT_FIELDS(FLAGS_BIT_FIELDS)
 #undef FLAGS_BIT_FIELDS
 
   STATIC_ASSERT(20 <= MinimumFractionDigitsBits::kMax);
   STATIC_ASSERT(20 <= MaximumFractionDigitsBits::kMax);
+  STATIC_ASSERT(Style::DECIMAL <= StyleBits::kMax);
+  STATIC_ASSERT(Style::PERCENT <= StyleBits::kMax);
+  STATIC_ASSERT(Style::CURRENCY <= StyleBits::kMax);
+  STATIC_ASSERT(Style::UNIT <= StyleBits::kMax);
 
   DECL_ACCESSORS(locale, String)
   DECL_ACCESSORS(icu_number_formatter,

test/intl/number-format/unified/percent.js

+// Copyright 2019 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --harmony-intl-numberformat-unified
+//
+// Test the handling of "percent" w/ "unit"
+
+let nf1 = new Intl.NumberFormat("en-US", {
+  style: "percent",
+  unitDisplay: "long"  // Read, but ignored.
+});
+
+let resolved1 = nf1.resolvedOptions();
+assertEquals("percent", resolved1.style);
+assertEquals(undefined, resolved1.unit);
+assertEquals(undefined, resolved1.unitDisplay);
+
+let parts1 = nf1.formatToParts(100);
+assertEquals(4, parts1.length);
+assertEquals("integer", parts1[0].type);
+assertEquals("10", parts1[0].value);
+assertEquals("group", parts1[1].type);
+assertEquals(",", parts1[1].value);
+assertEquals("integer", parts1[2].type);
+assertEquals("000", parts1[2].value);
+assertEquals("percentSign", parts1[3].type);
+assertEquals("%", parts1[3].value);
+
+let nf2 = new Intl.NumberFormat("en-US", {
+  style: "unit",
+  unit: "percent",
+  unitDisplay: "long"  // This is OK
+});
+
+let resolved2 = nf2.resolvedOptions();
+assertEquals("unit", resolved2.style);
+assertEquals("percent", resolved2.unit);
+assertEquals("long", resolved2.unitDisplay);
+
+let parts2 = nf2.formatToParts(100);
+assertEquals(3, parts2.length);
+assertEquals("integer", parts2[0].type);
+assertEquals("100", parts2[0].value);
+assertEquals("literal", parts2[1].type);
+assertEquals(" ", parts2[1].value);
+assertEquals("unit", parts2[2].type);
+assertEquals("percent", parts2[2].value);
+
+let nf3 = new Intl.NumberFormat("en-US", {
+  style: "unit",
+  unit: "percent"
+});
+
+let resolved3 = nf3.resolvedOptions();
+assertEquals("unit", resolved3.style);
+assertEquals("percent", resolved3.unit);
+assertEquals("short", resolved3.unitDisplay);
+
+let parts3 = nf3.formatToParts(100);
+assertEquals(2, parts3.length);
+assertEquals("integer", parts3[0].type);
+assertEquals("100", parts3[0].value);
+assertEquals("unit", parts3[1].type);
+assertEquals("%", parts3[1].value);

test/intl/number-format/unified/style-unit.js

@@ -19,7 +19,7 @@ nf = new Intl.NumberFormat("en", {style: 'currency', currency: 'TWD'});
 assertEquals(undefined, nf.resolvedOptions().unit);
 
 nf = new Intl.NumberFormat("en", {style: 'percent'});
-assertEquals('percent', nf.resolvedOptions().unit);
+assertEquals(undefined, nf.resolvedOptions().unit);
 
 assertThrows(() => new Intl.NumberFormat("en", {style: 'unit'}), TypeError);
 

test/intl/number-format/unified/unit-display.js

@@ -21,7 +21,7 @@ nf = new Intl.NumberFormat("en", {style: 'unit', unit: "meter"});
 assertEquals("short", nf.resolvedOptions().unitDisplay);
 
 nf = new Intl.NumberFormat("en", {style: 'percent'});
-assertEquals("short", nf.resolvedOptions().unitDisplay);
+assertEquals(undefined, nf.resolvedOptions().unitDisplay);
 
 const testData = [
     ["short"],