Fix division by zero in RenderTable intrinsic size methods (#178217)

## Description

This PR fixes a division by zero crash in `RenderTable` when intrinsic
size methods are called on empty tables (0 rows × 0 columns) with
non-zero constraints.

### The Problem

When `RenderTable` has 0 columns and intrinsic size methods
(`computeMinIntrinsicHeight`, `computeMaxIntrinsicHeight`,
`computeMinIntrinsicWidth`, `computeMaxIntrinsicWidth`) are called with
non-zero width constraints, the code calls `_computeColumnWidths()`
without checking if the table is empty. This leads to division by zero
at line 1140:

```dart
final double delta = (minWidthConstraint - tableWidth) / columns;
// When columns = 0, this crashes with division by zero
```

### The Solution

Added early return checks `if (rows * columns == 0) return 0.0;` to all
four intrinsic size methods, matching the pattern already used by other
methods that call `_computeColumnWidths()`:

- `computeDryBaseline` (line 1242) - already has the check
- `computeDryLayout` (line 1274) - already has the check
- `performLayout` (line 1318) - already has the check
- `paint` (line 1461) - already has the check

Now all four intrinsic methods are consistent with the rest of the
codebase.

### Testing

Added comprehensive test coverage (`Empty table intrinsic dimensions
should not crash`) that:
- Creates an empty table (0×0)
- Calls all four intrinsic size methods with various constraints
- Verifies they return 0.0 without crashing

### Changes Made

**packages/flutter/lib/src/rendering/table.dart:**
- Added empty table check to `computeMinIntrinsicWidth` (line 963-965)
- Added empty table check to `computeMaxIntrinsicWidth` (line 978-980)
- Added empty table check to `computeMinIntrinsicHeight` (line 995-997)
- Added empty table check to `computeMaxIntrinsicHeight` (line
1016-1019)

**packages/flutter/test/rendering/table_test.dart:**
- Added test case `Empty table intrinsic dimensions should not crash`
- Tests all four intrinsic methods with both finite and infinite
constraints

## Related Issues

This fix addresses a potential crash when using `RenderTable` with
intrinsic sizing widgets (like `IntrinsicHeight`, `IntrinsicWidth`) on
empty tables.

## Checklist

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checking the relevant checkboxes (`[x]`). This will ensure a smooth
review process.

- [x] I have read the [Contributor Guide] and followed the process
outlined there for submitting PRs.
- [x] I have read the [Tree Hygiene] wiki page, which explains my
responsibilities.
- [x] I have read and followed the [Flutter Style Guide], including
[Features we expect every widget to implement].
- [x] I have signed the [CLA].
- [x] I have listed at least one issue that this PR fixes (defensive
programming for edge case).
- [x] I have updated/added relevant documentation (doc comments with
`///`).
- [x] I have added new tests that verify the fix works.
- [x] All existing and new tests are passing (`flutter analyze` shows no
issues).
- [x] I have followed the [breaking change policy] and added [Data
Driven Fixes] where applicable (no breaking changes in this PR).

[Contributor Guide]:
https://github.com/flutter/flutter/blob/master/docs/contributing/Tree-hygiene.md#overview
[Tree Hygiene]:
https://github.com/flutter/flutter/blob/master/docs/contributing/Tree-hygiene.md
[Flutter Style Guide]:
https://github.com/flutter/flutter/blob/master/docs/contributing/Style-guide-for-Flutter-repo.md
[Features we expect every widget to implement]:
https://github.com/flutter/flutter/blob/master/docs/contributing/Style-guide-for-Flutter-repo.md#features-we-expect-every-widget-to-implement
[CLA]: https://cla.developers.google.com/
[breaking change policy]:
https://github.com/flutter/flutter/blob/master/docs/contributing/Tree-hygiene.md#handling-breaking-changes
[Data Driven Fixes]:
https://github.com/flutter/flutter/blob/master/docs/contributing/Data-driven-Fixes.md

---------

Co-authored-by: Kate Lovett <katelovett@google.com>

packages/flutter/lib/src/rendering/table.dart

@@ -960,6 +960,9 @@ class RenderTable extends RenderBox {
   @override
   double computeMinIntrinsicWidth(double height) {
     assert(_children.length == rows * columns);
+    if (rows * columns == 0) {
+      return 0.0;
+    }
     var totalMinWidth = 0.0;
     for (var x = 0; x < columns; x += 1) {
       final TableColumnWidth columnWidth = _columnWidths[x] ?? defaultColumnWidth;
@@ -972,6 +975,9 @@ class RenderTable extends RenderBox {
   @override
   double computeMaxIntrinsicWidth(double height) {
     assert(_children.length == rows * columns);
+    if (rows * columns == 0) {
+      return 0.0;
+    }
     var totalMaxWidth = 0.0;
     for (var x = 0; x < columns; x += 1) {
       final TableColumnWidth columnWidth = _columnWidths[x] ?? defaultColumnWidth;
@@ -986,6 +992,9 @@ class RenderTable extends RenderBox {
     // winner of the 2016 world's most expensive intrinsic dimension function award
     // honorable mention, most likely to improve if taught about memoization award
     assert(_children.length == rows * columns);
+    if (rows * columns == 0) {
+      return 0.0;
+    }
     final List<double> widths = _computeColumnWidths(BoxConstraints.tightForFinite(width: width));
     var rowTop = 0.0;
     for (var y = 0; y < rows; y += 1) {

packages/flutter/test/rendering/table_test.dart

@@ -401,4 +401,26 @@ void main() {
     expect(table.size, equals(size));
     expect(table.defaultVerticalAlignment, TableCellVerticalAlignment.intrinsicHeight);
   });
+
+  test('Empty table intrinsic dimensions should not crash', () {
+    // Test that empty tables (0 rows x 0 columns) don't cause division by zero
+    // when intrinsic size methods are called with non-zero constraints.
+    final table = RenderTable(textDirection: TextDirection.ltr);
+
+    // Verify table is empty
+    expect(table.rows, equals(0));
+    expect(table.columns, equals(0));
+
+    // These should all return 0.0 without crashing (previously caused division by zero)
+    expect(table.getMinIntrinsicWidth(100.0), equals(0.0));
+    expect(table.getMaxIntrinsicWidth(100.0), equals(0.0));
+    expect(table.getMinIntrinsicHeight(100.0), equals(0.0));
+    expect(table.getMaxIntrinsicHeight(100.0), equals(0.0));
+
+    // Also test with infinite constraints
+    expect(table.getMinIntrinsicWidth(double.infinity), equals(0.0));
+    expect(table.getMaxIntrinsicWidth(double.infinity), equals(0.0));
+    expect(table.getMinIntrinsicHeight(double.infinity), equals(0.0));
+    expect(table.getMaxIntrinsicHeight(double.infinity), equals(0.0));
+  });
 }