Fix Layout.primaryIsTrailingPreviousAllLineOffsets

Fix Layout.primaryIsTrailingPreviousAllLineOffsets

The CL fixes a crash in Layout.primaryIsTrailingPreviousAllLineOffsets.
The crash was happening when the method was called for a line beginning
with an empty bidi run. This could happen, for example, for empty text -
I was unable to find any other case. The CL improves the existing test
for the method with this case, which was previously crashing.

The CL also fixes a potential crash in getLineHorizontals. However, this
bug could never happen as in the current code path clamped is always
false (and kept as parameter for parity with getHorizontal).

Bug: 135444178
Test: atest FrameworksCoreTests:android.text.LayoutTest\#testPrimaryIsTrailingPrevious
Change-Id: I47157abe1d74675884734e3810628a566e40c1b4