Created a G class enum to reference class names returned in search
results. As noted in the class doc, this should only be used/updated as
a last resort, as class names change frequently. For some instances,
such as replacing the tbm tab, it's a lot easier to just replace by
header name than attempting to replace it based on how the element is
structured.
Also updated a few styles to revert the latest styling changes being
applied by Google.
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