RFR: 8344668: Unnecessary array allocations and copying in TextLine

[Daniel Gredler]

When `LineBreakMeasurer` is used to break text into lines, internally it uses `TextMeasurer` and `TextLine` to do the job. In the common case, `TextLine.getComponents(...)` allocates a `TextLineComponent[]` with room for a single array entry, and passes it to `TextLine.createComponentsOnRun(...)`, which fills the array and returns it, optionally resizing to a larger array if necessary, after which the array is resized back down to actual size (if necessary).

Unfortunately `TextLine.createComponentsOnRun(...)` is too eager in allocating larger arrays. In the most common case of a single component, this means that a single-element array is allocated, then a 9-element array is allocated (via `expandArray(...)`), and then another single-element array is allocated (to shrink the array back to actual size). Only one array allocation is necessary in this common case, and no array copying is needed.

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Commit messages:
 - Avoid unnecessary array allocations and copying in TextLine

Changes: https://git.openjdk.org/jdk/pull/22288/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=22288&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8344668
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/22288.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22288/head:pull/22288

PR: https://git.openjdk.org/jdk/pull/22288