Add flags for all layout qualifiers, check for duplicates

Now, even if a qualifier has a default value, we will know that it
appeared in the text. We can use that to check for redundant qualifiers
(as is being done here), and in the IR generator to prevent any use of
certain qualifiers, depending on context. (eg, runtime effects, wrong
shader stage, on a parameter declaration, etc.)

Bug: skia:11301
Change-Id: I2cd6ad35c2b4c4d6f87ade97e80aea84dc16ee4b
Commit-Queue: Brian Osman <>
Reviewed-by: John Stiles <>
12 files changed