[vector_graphics_compiler] Fix HSL color parsing for decimal percentage components

[fondoger]

Description

Fixes a bug in the HSL color parser where decimal percentage components
(e.g. 76.2745098039%) were incorrectly multiplied by 2.55 — the
conversion factor used for rgb percentages (percent → 0–255). For
hsl, saturation and lightness must stay in the 0–100 range (later
divided by 100) so the multiplication produced wildly wrong values
(e.g. 76.27 → 194, then 194 / 100 = 1.94).

The same branch also mis-handled the hsla alpha component: a unitless
decimal like 0.5 should be converted to 0–255 via × 255, not × 2.55.

Root cause

parser.dart checked rawColor.contains('.') and unconditionally
applied * 2.55, regardless of whether the current function was
rgb()/rgba() (correct) or hsl()/hsla() (incorrect).

Fix

Track whether each token had a % suffix before stripping it.
For HSL percentage components, return the raw double (0–100 range).
For unitless alpha decimals (0–1 range), multiply by 255.

Reproduction (from issue #185833)

hsl(270, 100%, 76.2745098039%)

Before fix	After fix
#efdeff ❌	#c286ff ✓

Tests

Four new tests added to parsers_test.dart:

• hsl with integer percentages (regression)
• hsl with decimal lightness percentage (the reported bug)
• hsla with integer percentages + decimal alpha (regression)
• hsla with decimal lightness + decimal alpha (combined case)

Related Issues

Fixes flutter/flutter#185833

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[gemini-code-assist]

Code Review

This pull request updates the SVG parser to correctly handle HSL and HSLA color strings, specifically addressing issues with decimal percentages in lightness and decimal values in alpha channels. It changes the internal storage of color components to num to preserve precision during parsing and adds comprehensive tests for various HSL/HSLA formats. I have no feedback to provide.